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Multi-sex systems
Posted: Posted November 7th, 2008 by bloodb4roses

We all know and understand (I hope) how sexes in Earth species work and different ways they are differentiated (genes, incubation, environment...) in various species. I've been getting ideas for a three-sexed species and was wondering what others' ideas for systems for more than two sexes could work, especially the ranges of 3-7 sexes.

My thought for a three-sex system based on genetics and alternate ganerations... "Females" in this species are AA, "males" are BB, and "neutrois" are AB where A and B are codominant. Males and females can produce offspring which will all be neutrois.

This is where I could go one of two ways. Have two neutrois being able to mate, producing males, females and (mostly) other neutrois. Or I could have neutrois produce children through parthogenesis, where only males and females would be produced, because of meiosis and reduplication for a full set of genes. I'm leaning toward mating, but that throws the sex ratios out of whack, unless there is some other reason for few neutrois children being born to neutrois parents...

I'm also thinking about a five-gender system for Vren, but as they're spirits I can be a little more "Just because!" with them.

So... Ideas? Comments?

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For my expanded Universe concept, for which I plan to incorporate my main conworld, I've been thinking about adding a three-sex sapient species. This species would resemble a tentacled fish-like creature which, in addition to breathing Oxygen, needs to inhale a certain amount of water vapour/mist as well. I'm not sure exactly how this would work, but I'm working on it.

The three sexes are: Female, sub-male, and full male. The way I plan to do this is by addind an extra sex chromosome. The species reproduces externally, with the female laying her eggs in a shallow pool of water, and then a full male inseminating them. Every female contributes two chromosomes which are linked. She usually distributes an equal amount of X and Y chromasomes but sometimes there are extra X chromasomes. When this happens, along with a lot of XY joined chromasomes, there are also a few XX chromasomes. Sometimes there are also a greater amount of single Y chromasomes but, since only X chromasomes can initiate a link with other chromasomes, these extra Y chromasomes do not find partners and so do not form eggs. Each egg needs to have atleast one X chromasome, as most Sexually reproducing Earth organisms do, which is why only X chromasomes can find partners and not Y chromasomes.

The second chromasome (either a Y or an X) produced by the female is called a secondary chromasome. Y's produced by a female always do the same thing when they are linked before fertilization by the male, but X's change their function when joined onto another X from the female preceding fertilization. Whereas the first X will contribute to brain growth as well as a few other functions, the second X contributes to a more passive and docile temperament. It also prevents the production of male gametes (sperm) so, if it joins with a Y chromasome given by the male, then the offspring will be infertile. These are the sub-males I mentioned. Sub-males can also be born if a linked XY chromasome from the female links with an X chromasome from the male. If a linked XX xhromasome from the female joins with an X chromasome given by the male, it becomes female.

So what does the female's Y chromasome do? Depending on what the third chromasome provided by the male is, it also does different things. Unlike the female's secondary X chromasome, however, the Y chromasome decides its role after fertilization instead of before. If a linked XY chromasome pair meets with an X from the male, the female's Y will cancel out the X's ability to produce eggs. This again leads to infertility and the birth of a sub-male. If, however, a paired XY chromasome meets with a Y from the male, it not only permits the male's Y to produce sperm, it also gives the offspring an assertive and aggressive personality. Such individuals are born fully male and, upon reaching sexual maturity, are driven to kill just about any other male (or any other being for that matter) in an attempt to find a female's dwelling and fertilize her eggs.

After fertilizing the eggs (or if he even makes it that far), the male's Y chromosome, given by his father, triggers an "automatic suicide" reaction in the rest of the body which then shuts down and the male dies. This function is triggered after the male expells the sperm stored in his body for fertilization. Upon sexual maturity, the production of sperm triggers the male's aggressiveness. The more sperm that is created, the higher the male's aggression and desire to expell his sperm. So in the males of this species, there is a link between testosterone production and aggression. Which is pretty much like how it is among many Earth animals.

The thought behind this was that, since female offsprime are relatively rare in comparison to sub- and full males, they would need a way to narrow down which males would pass on their genes and thus allow sexual selection to occur. And since females produce so many eggs at a time (over 100 eggs in a clutch, a new clutch every four years), males' competitions also help to lower the [male] population.

How this affects the culture:

Obviously this is going to be a matrifocal and matrilocal culture (or series of cultures if I get that far) so I'm going to say that each female owns her own house. I think I will make the societies matriarchal too, since the males have much shorter lives and are driven by anarchy, and sub-males are both more numerous and completely useless as far as reproduction goes. The females will, in turn, belong to a family council where each female is related, and this council will govern particular areas as city-states. As the societies discover one another and become more technologically advanced, they can become nation-states led by an elected queen. And new queens are only elected once an older one dies.

Posted November 7th, 2008 by Cerne
Cerne
 

Three sexes could be a huge advantage in an intelligent and organized species (more genetic diversity in offspring for each generation). If all three are mandatory, though, it's a disadvantage to less social species where the sexes might have trouble all meeting up at once.

If all three are not mandatory, and it is not an organized social species, then the ability to incorporate three sexes would probably be lost over time (since it would provide no real benefit)

One could include a more open form of gamete DNA exchange as found in bacterium, perhaps the female capable of mixing a pool of sperm or eggs... but that's not so much three sexes as X sexes.

There's probably a point of diminishing returns even in an intelligent and organized social species where the genetic diversity isn't worth all of the trouble of collecting all of the sexes for one fiasco.



EDIT:

Oh, right- the best way to incorporate more sexes would be to have an organism made up of several two sexed species (like a lichen, but an animal), where each species has to procreate- that results in as many mandatory sexes as you need (just make a multidimensional table of the possibilities).

Posted November 8th, 2008 by Blake
Blake
 

To me, one big question is, how many parents does each member of the species have?

If each one has just two parents (say, a father and a mother), then "sex" is a synonym for "outcrossing class"; that is, what's important about an animals sex is, what other sexes it can mate with, and which ones it can fertilize and thus become a father, and which ones it can be fertilized by and thus become a mother.

But suppose each organism has, say, three parents?

Then an important question is; Does an act of mating require all three parents to participate simultaneously? Do they all have to be there at once?

To me this seems to be an unlikely requirement; that is, it seems it would be a selective disadvantage. Much likelier, one parent would have to mate with each of the other two parents, perhaps in a particular order or within a particular maximum-allowed time of delay; but the other two parents never even need to meet each other nor know who each other are.

Consider which species of animals are hermaphroditic; that is, each individual is capable of becoming a mother and also of becoming a father; in each mating, either one could fertilize the other or be fertilized by the other.

These are the animal-species which are rare enough that they can't afford the possibility that, when two adults meet, they can't have reproductive copulation with each other because they're the same sex. For them, it's a selective advantage to remain hermaphroditic.

For animals which have a slightly less difficult time (even though it's still kinda tough!) finding a date on Saturday night, it seems to be more advantageous to know, before you even start out, which of you will be the father and which the mother (if you mate).

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One weird possibilty;
Each organism has just two parents, one mother and one father; but there are three sexes (A, B, and C).
If an A and a B mate, the A is the father and the B is the mother.
If a B and a C mate, the B is the father and the C is the mother.
If a C and an A mate, the C is the father and the A is the mother.

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Another possibility;
Each organism has just two parents, one father and one mother.
There are three sexes; males, females, and hermaphrodites.
Males cannot mate with males.
Males can mate with either females or hermaphrodites; if they do, the male is the father and the other is the mother.
Females cannot mate with females.
Females can mate with either males or hermaphrodites; if they do, the female is the mother and the other is the father.
Hermaphrodites can mate with anyone. If a hermaphrodite mates with a male, the hermaphrodite becomes the mother; if a hermaphrodite mates with a female, the hermaphrodite becomes the father; and if two hermaphrodites mate with each other, one becomes the father and one becomes the mother, but it's unpredictable which.

Or; there could be males, females, and two different kinds of hermaphrodites, such that hermaphrodites couldn't mate with the same kind of hermaphrodite.

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Centauroids might be made up of a humanoid conjoined with an equinoid. There could be man-stallion, man-mare, woman-stallion, and woman-mare individuals. How that would work out I don't know.

The way it worked in "Well of Souls" was;
A man-stallion's or man-mare's "man-" part mated with a woman-stallion's or woman-mare's "woman-" part; "she" then laid an egg which was taken into the uterus of the "-mare" part of a man-mare or woman-mare; then it was fertilized by the "stallion" part of a man-stallion or woman-stallion; then the mare gave birth to a new centaur.
A new individual could have as few as two or as many as four parents that way. If it had just two, they could as likely be a man-mare and a woman-stallion, as a man-stallion and a woman-mare.

Posted November 8th, 2008 by chiarizio

We all know and understand (I hope) how sexes in Earth species work and different ways they are differentiated (genes, incubation, environment...) in various species. I've been getting ideas for a three-sexed species and was wondering what others' ideas for systems for more than two sexes could work, especially the ranges of 3-7 sexes.

My thought for a three-sex system based on genetics and alternate ganerations... "Females" in this species are AA, "males" are BB, and "neutrois" are AB where A and B are codominant. Males and females can produce offspring which will all be neutrois.

This is where I could go one of two ways. Have two neutrois being able to mate, producing males, females and (mostly) other neutrois. Or I could have neutrois produce children through parthogenesis, where only males and females would be produced, because of meiosis and reduplication for a full set of genes. I'm leaning toward mating, but that throws the sex ratios out of whack, unless there is some other reason for few neutrois children being born to neutrois parents...

I'm also thinking about a five-gender system for Vren, but as they're spirits I can be a little more "Just because!" with them.

So... Ideas? Comments?
On Earth nearly all sexually-reproducing species have "alternation of generations"; monoploid specimens produce diploid specimens which produce monoploid specimens which produce diploid specimens which ... etc.

In the earlier, and currently in the more primitive, sexually-reproducing species, the larger and longer-lived specimens were all monoploid; two of them had to meet and mate to produce a zygote (a diploid specimen), which usually remained small and was short-lived and produced several monoploid offspring via meiosis.

In the later more advanced sexually-reproducing species, the larger and longer-lived specimens were all diploid; they produce several monoploid gametes by meiosis, and these gametes meet other gametes, and fuse into a diploid zygote which then grows up to be another longer-lived, larger specimen. (Humans are these, of course; sperm and ova are the gametes, and cannot survive for long without support from the body of their parent diploid specimen.)

But there are a few species in which both the monoploid "gametes" and the diploid "zygotes" grow up into relatively-large, relatively-long-lived, free and independent organisms. Why couldn't this happen to your species? You could have three sexes; the As (monoploid), the Bs (monoploid), and the ABs. As have to mate with Bs, and Bs have to mate with As, to have offspring, all of which have to be ABs; then the ABs reproduce parthenogenetically, and all of their children are either As or Bs (about half are As and about half are Bs).

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If all of your specimens are diploid, and all XX are female and all female are XX, and all YY are male and all male are YY, and the offspring of a mating of an XX with a YY is always an XY; then, if an XY can mate with another XY, we would expect about a quarter of the offspring to be XX female, about a quarter to be YY male, and about half to be XY.

I don't see why that would be an advantage.

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The advantage of sexual reproduction applies to organisms that need longer to reproduce; those that need to grow up some before they can mate; the bigger ones; the multi-cellular ones.

The thing is, single-celled, asexually-reproducing organisms, can have very short generation-times, which can mean they can evolve very very quickly.

If a large, multi-celled organism needs a long generation time (and it probably does), then if it reproduces only asexually, it evolves quite slowly; because the number of beneficial mutations per generation is probably about the same for them as for the one-celled fast-breeders, some of which may "prey" on them.

Recombining genes, by sexual reproduction, is a way of "spinning the locks" between one generation and the next. The one-celled fast-breeding predators may have evolved to be able to attack each parent, but those techniques may not necessarily work on the offspring; and one that works on one of the offspring won't necessarily work on any other offspring, not even if the two offspring share both parents.

Obviously this advantage would be even greater if every specimen had three parents instead of just two; but under what circumstances would that advantage actually be necessasry? Maybe the specimens are very big and very long-lived? Maybe they have to grow up a very long time in order to reproduce? Maybe they have to wait a very long time between one child and the next? If they are always immersed in a huge and diverse population of very small, very quick-breeding "predators" or parasites, this might be really important.

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Kudzu, on Earth, in Real Life, have eight sexes.
Each plant has three sex organs.
One is short, one is long, and one is middle-length.
Each sex-organ can be either male (stamen) or female (pistil).

A short stamen can fertilize only a long pistil; a long pistil can be fertilized only by a short stamen.
A long stamen can fertilize only a short pistil; a short pistil can be fertilized only by a long stamen.
A middle-length stamen can fertilize only a middle-length pistil; a middle-length pistil can be fertilized only by a middle-length stamen.

So, one sex -- the one with three stamens -- can fertilize each of the other sexes, but can't be fertilized by anything.
One sex -- the one with three pistils -- can be fertilized by each of the other sexes, but can't fertilize anything.
The two sexes with a long stamen and a short stamen, or the two sexes with a long pistil and a short pistil, are outcrossing classes; they can't fertilize, nor be fertilized by, other members of their own sex. (But the ones with a middle-length stamen can fertilize the ones with a middle-length pistil).
The two sexes with a long stamen and a short pistil can fertilize and be fertilized by each other and also by members of their own sex; likewise the two sexes with a short stamen and a long pistil can fertilize and be fertilized by each other and also by members of their own sex.
For each sex, there is a sex with which it is totally incompatible -- it can't fertilize it, nor be fertilized by it. For four of them, this is their own sex. For the other four, it's some other sex.

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The parent that pays the highest biological cost is the parent that gets called "the mother".
Usually -- in fact I know of no exception -- this is the parent that contributes all the genetic information that the offspring gets from only one parent (for instance, cytoplasmic or mitochondrial DNA).

Posted November 8th, 2008 by chiarizio

I've been toying with an idea for a more humanoid race of water elementals, actually. Not sure how relevant it would be, mostly due to the alien nature of their forms, but I'll toss it out there anyway. It's not fully developed, and any references to chromosomes are purely referential in nature and should be taken at face value.

They would maintain a similar biological concept to the XX/XY dichotomy, reproductively speaking, while being utterly different and incompatible with other species. The idea is more of an ooze-like creature in substance, encased in a wall of more rigid "skin" that is only susceptible to the same substance (that is, willingly - physical trauma could still rupture the "skin" just as it would humans) at a certain point in the year. That point in the year would, naturally, be their mating season.

When this period occurs, males and females (typically - male/male and female/female combinations could do so as well, but for the sake of this explanation, I'll stick with male/female) seek out potential partners. Rather than a sexual mating, they would physically merge for 4-6 weeks, during which their cells would mingle and merge, in a process similar to osmosis, creating an XXXY chromosomal combination for the duration, which would multiply over time (XXXXYY, or XXXXXY, depending on the outcome). When the gestation period ends, the parental entity's chromosomes would divide evenly into three separate beings - the mother, the father, and the offspring - which while retaining their individual minds, could have either gender specification as an end result. Should they fail to produce offspring (most likely by being forced to divide too soon), then the parents simply become two creatures with a combination of three chromosomes (XXY/XXY, or XXX/XXY)

Such creatures would have, effectively, six genders that could potentially change as frequently as year to year: Male (XY), Protomale (XXY - uneven split - distinguished by favouring male physical traits), Merged(XXXY), Neuter (XXY - even split - distinguished as being almost perfectly androgynous), Protofemale (XXX), Female (XX).

Protomales, Neuters, and Protofemales would have a slightly more difficult time with the mating process, and be seen as quite fortunate by many, while also being assisted by most others in finding a suitable mate. Such genders would require another of their sort (triple chromosome) in order to reproduce, but rather than producing a single offspring, theirs would result in the creation of a multiple birth (which could result in multiple different combinations that I won't bother to type out right now) or a single birth (if divided prematurely).

Of course, that's all just a theory. I've got no clue if I'll ever get around to designing them beyond that, mostly due to the complexities of the psychological state that such a race would exist in. :P

Posted November 8th, 2008 by Tharivious

This isn't a 3-way system, but I once had a pleasantly screwed up system with hermaprodites and asexuals. Hermaphrodites had the sex chromosomes HA. Only they could reproduce. So, of their offspring, half would be fertile hermaphrodites, a quarter sexless and sterile (AA) and a quarter would be HH---inviable. Luckily for them they were geographically isolated and not much was competing with them.

I also have a system that's pretty much A/B/AB. Or it will be if I decide to have two sexes in the haploid stage.

Posted November 9th, 2008 by lryda mbazha

First:
All other respondents to this thread have clearly put some thought and work into this. I thank you all.

Now, my main points:
When we talk about "sex" we're actually confounding two things that can really be separate;
(1) Which is the mother and which is the father, and
(2) Outcrossing classes.

(1) When a member of a sexually-reproducing species has two parents, they may both have equal and similar roles. In that case, neither is really the mother and neither is really the father.

Otherwise, one of several things (that are usually correlated) may happen:
(a) one parent may contribute more heredity than the other; if so that's the one we usually end up calling "the mother".
(b) one parent may contribute a larger, and/or less mobile, and/or longer-lived, and/or not-quite-so-dependent gamete than the other (and make fewer of them); if so we usually call that gamete "an ovum" and call that parent "the mother". The smaller, or more mobile, or shorter-lived, or less-independent gamete, produced in larger numbers, we call "the sperm", and that parent we call "the father".
(c) one parent may actually keep the zygote inside that parent's body for a time; if so we call that parent "the mother". (If the offspring is transferred to the other parent's body eventually, the one that has it first is still called "the mother").
(d) one parent may do more to take care of the young offspring, especially at first, than the other; that parent is usually called "the mother". (Later the father may do as much or more.)
(e) one parent's body may produce food for the offspring; that parent is called "the mother", if the other parent does not also do so.

A specimen which can become a father but can never become a mother is called "male", and a specimen which can become a mother but can never become a father is called "female". But a specimen which can become either a father or a mother is called "hermaphroditic".

- - - - -

(2) Many sexually-reproducing species are divided into "total outcrossing classes"; that is, each specimen is a member of one, and only one, class, and no member of any class can productively mate with any member (neither itself, nor any other) of the same class.

A species may be divided into more than two such outcrossing classes.

Naturally if a class consists of individuals who can only become fathers, never mothers, then it's a total-outcrossing class, since no two specimens which can only become fathers, could productively mate.

Similarly if a class consists of individuals who can only become mothers, never fathers, it's a total-outcrossing class.

We are used to the idea that a species will be divided into just two outcrossing classes; and that those two will be, males (who can become fathers but never mothers) and females (who can become mothers but never fathers).

But it doesn't have to be that way; in fact it's possible to have two total-outcrossing classes both consist of hermaphrodites.

Anyway; if a species consists of more than two outcrossing classes, a "mating matrix" can be set up, showing, for each pair of such classes, whether
(1) they cannot productively mate at all, or
(2) if they mate the first can be the father and the second the mother, but not vice-versa, or
(3) if they mate the first can be the mother and the second the father, but not vice-versa, or
(4) if they mate either one can be the mother and either one can be the father.

- - - - - - - - - - - - - - - -

The sex of a specimen does not have to be determined at conception.

Indeed there are crocodilians (very bird-like or dinosaur-like reptiles) whose sex, at hatching, is partly determined by what temperature they were incubated at as eggs.

If the specimen's sex is partially determined at conception, it may be determined by a single allele of a single locus on a single chromosome, or otherwise.

A subgroup of Old World Monkeys that happens to include all Apes, has a maleness-determining gene that goes on a chromosome called the Y chromosome; in these species normal males are XY and normal females are XX. In the strict sense the Y chromosome does not occur in other species, not non-monkey primates, not New World Monkeys, and not even all Old World Monkeys; nevertheless, other species with a maleness-determining gene are said to "have an XX/XY system".

Some animals, (including some vertebrates, including all birds and some fish), have a femaleness-determining gene; it occurs on a chromosome called the W chromosome. Among these species males are ZZ and females are ZW. These species are said to "have a ZW/ZZ system".

But some animals don't have sex-chromosomes; instead they have sex-loci on some of their somatic chromosomes. If they have more than one such loci that complicates things; or if one (or more) such locus has more than two alleles that complicates things.

For instance, suppose the alleles of one locus were M and m, and the alleles of another were N and n. Perhaps all nine phenotypes MMNN, MMNn, MMnn, MmNN, MmNn, Mmnn, mmNN, mmNn, mmnn were viable. If so, some environmental factor might determine which ones became male and which ones became female; or there might be more than two sexes.

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In Piers Anthony's Tarot universe is a three-sexed species in which every specimen has three parents, one of each sex. Each individual of a given sex could be the mother of an offspring of exactly one sex (not the same as the mother's sex). All three parents have to participate at once to make the mating fertile. The question of which parent becomes pregnant, and what the sex of the offspring is, depends on what happens during the mating.
Suppose the parents are called A, B, and C (I'm so creative!). If an A and a B have begun mating, and a C joins them to complete the act, the A becomes pregnant with a B baby; if a B and a C have begun mating, and an A joins them to complete the act, the B becomes pregnant with a C baby; if a C and an A have begun mating, and a B joins them to complete the act, the C becomes pregnant with an A baby. (Or something like that.

In another story I read, there were four sexes: ultramales, males, females, and ultrafemales. Each specimen had three parents, no two of whom were the same sex as each other. The sex of the offspring was whatever sex none of its parents were.

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Something that happens occasionally in nature and frequently in the breeding technology that existed before Watson & Crick and the disovery of the double-helix structure of DNA, is tetraploidy. This especially occurs when farmers (or whoever) manage to successfully hybridize two species that are different enough not to interbreed in nature but similar enough that success is possible; for instance, nectarines are hybrids of peaches with plums. What happens is, for both members of the founding couple -- one from each species -- a gamete is produce via incomplete meiosis; it still has the entire diploid complement of its species' chromosomes, but it "thinks of itself" as a sperm or an ovum. Then these two are joined. All resultant offspring then have four copies -- or four versions -- of almost all of their genes (except those only one of the parent species had). If these hybrid offspring are then interfertile with each other, a new species has been created, which is (almost completely) tetraploid.

Tetraploids frequently have much more "hybrid vigor" than diploids do.

Tetraploidy could make for some interesting sex alchemy. For instance, suppose there was one sex-locus and it had two alleles, X and Y. The possible combinations, then, would be XXXX, XXXY, XXYY, XYYY, and YYYY. If all were viable you might have five sexes. Of course, you'd have to have a rule (not a socially-imposed one, but one imposed by the physiology or cellular biology of the species) that not every such phenotype could breed with every such phenotype (in particular not with itself); nor could any given phenotype both be able to fertilize, and be fertilizable by, each other phenotype with which it could, in fact, breed. Otherwise, this wouldn't be a sex-chromosome, it would just be an ordinary somatic chromosome.

One possibility that suggests itself is this:
XXXX and YYYY are non-viable; they don't implant in the mother's uterus, and don't divide.

XXXY are females and can only be mothers.
XYYY are males and can only be fathers.
XXYY are hermaphrodites who can fertilize XXXY females but not be fertilized by them, and can be fertilized by XYYY males but can't fertilize them.
XXXY females can mate with either XXYY hermaphrodites or XYYY males.
XYYY males can mate with either XXYY hermaphrodites or XXXY females.
XXYY hermaphrodites cannot mate with themselves nor with each other.

Now, in any mating, a female can contribute either an XX ovum or an XY ovum with equal probability; a male can contribute either an XY sperm or a YY sperm with equal probability; and a hermaphrodite can contribute either an XY gamete (50%) or an XX gamete (25%) or a YY gamete (25%).

So if an XXXY female and an XYYY male mate, one-half of their offspring will be XXYY hermaphrodites, one-quarter will be XXXY females, and one-quarter will be XYYY males.

If an XXXY female and an XXYY hermaphrodite mate, three-sevenths of their offspring will be XXXY female, three-sevenths will be XXYY hermaphrodite, and one-seventh will be XYYY male. (The XXXX won't be viable.)

If an XYYY male and an XXYY hermaphrodite mate, three-sevenths of their offspring will be XYYY male, three-sevenths will be XXYY hermaphrodite, and one-seventh will be XXXY female. (The YYYY won't be viable.)

Posted November 9th, 2008 by chiarizio

I just started a thread on my AB+A+B system, and a further complication thereof.
here

Posted November 9th, 2008 by lryda mbazha

So would my new conspecies be diploid or triploid? Nobody seems to have said anything against the idea so I goess it could still happen.

Posted November 9th, 2008 by Cerne
Cerne
 

Well there is actually a few syndromes where an extra chromosome is created during the early cell divisions in human pregnancy...

http://en.wikipedia.org/wiki/Klinefelter%27s_syndrome
http://en.wikipedia.org/wiki/Fragile_X_syndrome
http://en.wikipedia.org/wiki/Triple_X_syndrome
http://en.wikipedia.org/wiki/XYY_syndrome
http://en.wikipedia.org/wiki/XXXX_syndrome
http://en.wikipedia.org/wiki/XXXXX_syndrome

I threw the last 2 in to demonstrate the effects of multiple additional chromosomes to the physical and mental development of people.

Maybe something to think about when giving out extra chromosomes

Posted November 9th, 2008 by SaLien
SaLien
 

Well there is actually a few syndromes where an extra chromosome is created during the early cell divisions in human pregnancy...

[snip]

I threw the last 2 in to demonstrate the effects of multiple additional chromosomes to the physical and mental development of people.

Maybe something to think about when giving out extra chromosomes


Which is for humans and species on Earth, not counting some plants.

Posted November 9th, 2008 by bloodb4roses

Let's see... Back to my neutrois.

I think that it could add an interesting social dynamic if part of the population of this species were to reproduce completely pathogenically, as only one parent would be necessary to produce the two sexually reproducing sexes, and also an individual of the species would learn more about their sex/gender roles from their grandparents than their parents. Also, if the only individual left were neutrois, they could (possibly) repopulate an area by themself.

On the other hand, if the neutrois reproduced sexually with each other, it would be evolutionarily beneficial by mixing more of the genetics in each generation, making them more resistant against deseases and parasites.

In the first case, males and females would likely band together at "home" being more social while most neutrois would go off on their own, find new terratory and start new families or tribes. This would make them the most likely to be in the "alpha role" of the unit. They'd probably be terratorial and very fertile, producing a large number of offspring in their lifetime. Females and males might only couple if the neutrois died... (Or at least this is one possible mating strategy.)

In the second case, everyone might stay together, or neutrois would band together as one group and males and females might be another unit. The species as a whole might be less terratorial (I might have several bands of neutrois and several bands of males and females interacting often to reduce interbreeding.) This could lead to many interesting "marriage" ceremonies in different cultures. In either generation, children would have two parents, but would still be likely to learn more from grandparents or the unit they are adopted into than their own parents aside from the basics of getting food or such.

It would be fun to play with both ideas...

Posted November 10th, 2008 by bloodb4roses

Your plants could just grow the animals in them. Mammals are only warm blooded as a means to maintain a higher rate of metabolism and more efficient muscles. Sure, we've grown adapted to it, but there's no fundamental reason that it can't be turned off and on- hibernation case in point.

Your plants could grow cold blooded fetuses, which warm up once born.

Posted November 10th, 2008 by Blake
Blake
 

Whereas the first X will contribute to brain growth as well as a few other functions, the second X contributes to a more passive and docile temperament

? Could it be possible that a chromosome determines things like a person's attitude. I know it might determine what kind of flavors that person would prefer over other flavors, but that might be an interesting idea...

So far I've seen here that you exposed ideas about using X, X2 and Y chromosomes to procreate a new creature, but why didn't you just create a third chromosome, let's say it's Z, instead?

Could the following be reasonable for a conworld?

Let's say that there's a creature with female characteristics and another one with male ones. What if both of them require to find a "host" for the new babie / cub / whatever you wanna call it?

I'd say that the host would provide those characteristics that are commonly found in both creatures, let's say, the eye / hair color, height / weight, hands and feet size, etc.

The chromosomes would be distributed like this:

Male - 50% Y, 25% X, 25% Z
Female - 50% X, 25% Y, 25% Z
Host - 50% Z, 25% X, 25% Y

Another option would be...

Male - 60% Y, 10% X, 30% Z
Female - 60% X, 10% Y, 30% Z
Host - 60% Z, 20% X, 20% Y

The reason why the host would be more... balanced would be that it should support either a male baby or a female one.

Posted November 10th, 2008 by kyonides

So would my new conspecies be diploid or triploid? Nobody seems to have said anything against the idea so I guess it could still happen.
If they are triploid then odds are they have three parents per specimen.
If they are diploid then odds are they have two parents per specimen.
If they are tetraploid they might have two parents per specimen or they might have four parents per specimen.

None of the above, however, determines anything about how many sexes the species has.
A two-parents-per-specimen species might have one sex (hermaphrodites), two sexes (e.g. males and females), three sexes, or whatever.
The same with a three-parents species or a four-parents species.

I know of no triploid organisms in real life; that doesn't mean it couldn't happen. A DNA with 6 types of nucleotide-base instead of just 4 is also possible. A genetic code with 4 base-pairs per codon instead of just 3 is possible. Why wouldn't a triploid species be possible?

There are many inborn errors among humans in which one chromosome "pair" turns out to be monoploid or triploid instead of diploid.

"Downs's syndrome" (a.k.a. "mongoloid idiots", but that's not a good name) is usually either trisomy-19 or trisomy-21. A few other somatic chromosome-"pairs" can turn into trisomies and still survive until birth; "cri du chat" is one of them, IIANM. Most of the dysnumeric [edit]("aneuploid" is the correct term)[/edit] errors that survive long after birth, though, are in the sex-chromosomes; X0 (Turner's syndrome), XXY (Kleinfelter's syndrome), XXX (don't know the name), XYY (often no signs nor symptoms), and some with more than three sex-chromosomes, like XXXX, XXXY, XXYY, XYYY, or five or more sex-chromosomes. At least one must be an X; without an X-chromosome the zygote won't survive until birth, nor even develop well enough long enough for the mother to know she's been pregnant.

Among humans, except for sex-chromosomes, loss of a somatic chromosome -- a monoploidy in one "pair" -- is almost never viable; trisomy (a triploidy in one "pair") is likelier to be non-viable than viable, though there are several exceptions; and AFAIK tetrasomy is never viable (but maybe it is and I just don't know).

However, tetraploidy in plants, especially in artificially-induced hybrids of different species, is viable and happens quite a bit.

Also, there are species of animals that appear to be related except that one has twice as many chromosomes as the other; so, although no-one knows of an instance of tetraploidy in animals that has been viable during recorded history, apparently it's happened in the past.

-------------------------------------------------------------------------------------

I think that it could add an interesting social dynamic if part of the population of this species were to reproduce completely pathogenically,
parthenogenetically (from the Greek word "parthenos" originally meaning "barren" but later meaning "virgin".)
as only one parent would be necessary to produce the two sexually reproducing sexes, and also an individual of the species would learn more about their sex/gender roles from their grandparents than their parents. Also, if the only individual left were neutrois, they could (possibly) repopulate an area by themself.
I agree. You've thought parts of this out further than I have; learning one's gender role from one's grandparent rather than from one's parent is something I hadn't thought of yet, but you're right.

-------------------------------------------

a third chromosome, let's say it's Z, instead?

Could the following be reasonable for a conworld?

Let's say that there's a creature with female characteristics and another one with male ones. What if both of them require to find a "host" for the new babie / cub / whatever you wanna call it?

I'd say that the host would provide those characteristics that are commonly found in both creatures, let's say, the eye / hair color, height / weight, hands and feet size, etc.

The chromosomes would be distributed like this:

Male - 50% Y, 25% X, 25% Z
Female - 50% X, 25% Y, 25% Z
Host - 50% Z, 25% X, 25% Y

That's reasonable for a triploid species.
I'd call the "host" the mother, and thus the female. What you call the "female" I'd call "the other male sex".
Now the question is, how, with three parents per offspring, does the triploidy get maintained?

[EDIT]:
The change above was from "tetra-" to "tri-".
It was suggested by Cerne.
If everybody has three parents and each of your triploid (that is, each individual has three versions of each somatic chromosome) parents contributes just one chromosome from each of their triplets, the species will stay triploid.
Of course, even with three parents per offspring, there's a possibility the species could be tetraploid, if one sex always contributed two members of each quadruplet while each of the other two sexes just contributed one.
That's reasonable for a tetraploid species.
I'd call the "host" the mother, and thus the female. What you call the "female" I'd call "the other male sex".
Now the question is, how, with three parents per offspring, does the tetraploidy get maintained?

I think I was thinking that the act of reproduction required a "male" and a "female" and two "hosts", thus, four parents per offspring, and a possibility that an offspring might have four sex-chromosmes. Depending on the system, they'd all have four; or all have three (even though they all have four versions of each somatic chromosome); or some have four and some have three; or some have three and some have two; or various other arrangements, depending on the system, that still kept the tetraploid for somatic (i.e. non-sex) chromosomes.
[/EDIT]

-------------------------------------

Your plants could just grow the animals in them. Your plants could grow cold blooded fetuses, which warm up once born.
He's got a point.

Posted November 10th, 2008 by chiarizio

Sorry I took so long to reply. It's either dial-up at home or a public computer.

Well there is actually a few syndromes where an extra chromosome is created during the early cell divisions in human pregnancy...

[snip]

I threw the last 2 in to demonstrate the effects of multiple additional chromosomes to the physical and mental development of people.

Maybe something to think about when giving out extra chromosomes


Which is for humans and species on Earth, not counting some plants.


Thanks guys. This effectively stays within the confines of what I was working with while at the same time suggesting that it is possible to do something like it. So it helps me out a lot.

Only...do you think it could be a standard for this species instead of as an abnormality the way it is with humans?

I think that it could add an interesting social dynamic if part of the population of this species were to reproduce completely pathogenically, as only one parent would be necessary to produce the two sexually reproducing sexes, and also an individual of the species would learn more about their sex/gender roles from their grandparents than their parents. Also, if the only individual left were neutrois, they could (possibly) repopulate an area by themself.


If you chose this option, you may want to ask yourself why one parent could still produce two sexes if the species only needs one sex to reproduce. What's the use of a second sex if they can reproduce asexually, anyway? Yeah, it would be more evolutionarily beneficial but it would also be more inefficient I would think. Would either of these sexes be able to reproduce sexually, or would one be parthenogenic (<- that is the right spelling) like its parent?

On the other hand, if the neutrois reproduced sexually with each other, it would be evolutionarily beneficial by mixing more of the genetics in each generation, making them more resistant against deseases and parasites.


Sort of like hermaphrodites, then? I like this idea better. It fits in better with the two-sex system. I mean, you could see how something like this could appear in a once two-sex species.

So far I've seen here that you exposed ideas about using X, X2 and Y chromosomes to procreate a new creature, but why didn't you just create a third chromosome, let's say it's Z, instead?


Because, as chiarizio said, a third chromosome requires a third reproductive sex. I asked whether my new conspecies was diploid or triploid because I was unsure of the grounds for which I could call either.

It seems chiarizio clarified that in his latest post, though:

If they are triploid then odds are they have three parents per specimen.
If they are diploid then odds are they have two parents per specimen.


My conspecies has two reproductive sexes and, at the time, I wanted only two chromosomes (I was unaware that you could add additional chromosomes, or that organisms on Earth had already done this) so I just added the X and the Y. I already knew I wanted a third infertile sex that wpuld be more male than female so I tried to find a way to do this while only using two chromosomes. My conclusion now is that the conspecies is still essentially diploid but that it is capable of producing three sexes.

One way I had thought of for the origin of such a characteristic is that all diploid species on the planet do the same thing, but then there's no real purpose for the third sex so it probably would have been weeded out during their evolution unless it was a defect that later became standardized thoughout the entire species. Which might sound a bit unusual.

I have also thought about having this three sex system be the result of increased collectivism among the species' ancestors: over time, females began releasing chromosomes that were already linked instead of single chromosomes...still not sure exactly how this sort of thing could possibly have developed though, so suggestions would be welcomed and appreciated.

a third chromosome, let's say it's Z, instead?

Could the following be reasonable for a conworld?

Let's say that there's a creature with female characteristics and another one with male ones. What if both of them require to find a "host" for the new babie / cub / whatever you wanna call it?

I'd say that the host would provide those characteristics that are commonly found in both creatures, let's say, the eye / hair color, height / weight, hands and feet size, etc.

The chromosomes would be distributed like this:

Male - 50% Y, 25% X, 25% Z
Female - 50% X, 25% Y, 25% Z
Host - 50% Z, 25% X, 25% Y


That's reasonable for a [tri


"Tri-" = three, "tetra-" = four.

That does sound good. I don't think my new species could use it though, since they lay eggs...maybe the third sex could guard and look after the eggs? Just an idea.

Posted November 10th, 2008 by Cerne
Cerne
 

I think that it could add an interesting social dynamic if part of the population of this species were to reproduce completely pathogenically, as only one parent would be necessary to produce the two sexually reproducing sexes, and also an individual of the species would learn more about their sex/gender roles from their grandparents than their parents. Also, if the only individual left were neutrois, they could (possibly) repopulate an area by themself.


If you chose this option, you may want to ask yourself why one parent could still produce two sexes if the species only needs one sex to reproduce. What's the use of a second sex if they can reproduce asexually, anyway? Yeah, it would be more evolutionarily beneficial but it would also be more inefficient I would think. Would either of these sexes be able to reproduce sexually, or would one be parthenogenic (<- that is the right spelling) like its parent?


Because the neutrois would be AB (or WZ or XY or whatever you'd prefer to term it) and parthogenesis always makes individuals with two copies of each series of chromosomes. All children produced this way would either be AA or BB, ie either "males" or "females". Similarly, if the neutrois who was their parent was heterozygous for some trait (for example Purple skin but having a purple skin gene and a blue skin gene), all their children would either be homozygous Purple, or homozygous blue.

I already stated that males and females would reproduce sexually.

I do not want this world to follow Earth biology exactly, so there is no need for one sex allele to be mandatory for a fetus to be viable, and I've decided that the sex alleles would be codominant for this species.


On the other hand, if the neutrois reproduced sexually with each other, it would be evolutionarily beneficial by mixing more of the genetics in each generation, making them more resistant against deseases and parasites.


Sort of like hermaphrodites, then? I like this idea better. It fits in better with the two-sex system. I mean, you could see how something like this could appear in a once two-sex species.


Actually, I think I want this planet to have creatures that often have three sexes. Having one or two wouldn't be unheard of, but the majority of species would have three.

Posted November 10th, 2008 by bloodb4roses

It would be interesting if you had the 'plant' and 'animal' forms fertilizing or producing each other without them realizing it (for the humanoids).

Say, they don't realize where the plants are coming from, and if the fertilization is very obscure, they just suspect themselves of immaculately conceiving.

Posted November 11th, 2008 by Blake
Blake
 

Cerne, thank you for your positive response.
Naturally this post is barely going to mention all the nice things you said about my posts, and concentrate on the one place where you may have misunderstood me.

a third chromosome, let's say it's Z, instead?
The chromosomes would be distributed like this:
Male - 50% Y, 25% X, 25% Z
Female - 50% X, 25% Y, 25% Z
Host - 50% Z, 25% X, 25% Y

That's reasonable for a [tetra

"Tri-" = three, "tetra-" = four.

I wrote "tetraploid" because XYZZ, XYYZ, and XXYZ are all sets of four sex-chromosomes.

It was the XXYZ - XYYZ - XYZZ system that I meant was "reasonable for tetraploid species".

But the question of how tetraploidy could be maintained in a system in which each offspring had three parents -- an XXYZ parent, an XYYZ parent, and an XYZZ parent -- is a hard one for me.

The problem, of course, is that "three" doesn't match up with "four".

The only way I could see it working is if sometimes one parent contributes two chromosomes instead of one, but the other two parents each contribute one chromosme instead of two.

Here are some possibilities; note the huge number of "sterile" and "nonviable" combinations.

If the "host" contributes two chromosomes, and both the "mother" and the "father" contribute one each;
"Mother"'s Contribution: X. "Father"'s Contribution: X. "Host"'s Contribution: YZ. Offspring's Result: XXYZ "female".
"Mother"'s Contribution: X. "Father"'s Contribution: Y. "Host"'s Contribution: XZ. Offspring's Result: XXYZ "female".
"Mother"'s Contribution: X. "Father"'s Contribution: Z. "Host"'s Contribution: XY. Offspring's Result: XXYZ "female".
"Mother"'s Contribution: Y. "Father"'s Contribution: X. "Host"'s Contribution: XZ. Offspring's Result: XXYZ "female".
"Mother"'s Contribution: Z. "Father"'s Contribution: X. "Host"'s Contribution: XY. Offspring's Result: XXYZ "female".
"Mother"'s Contribution: X. "Father"'s Contribution: Y. "Host"'s Contribution: YZ. Offspring's Result: XYYZ "male".
"Mother"'s Contribution: Y. "Father"'s Contribution: X. "Host"'s Contribution: YZ. Offspring's Result: XYYZ "male".
"Mother"'s Contribution: Y. "Father"'s Contribution: Y. "Host"'s Contribution: XZ. Offspring's Result: XYYZ "male".
"Mother"'s Contribution: Y. "Father"'s Contribution: Z. "Host"'s Contribution: XY. Offspring's Result: XYYZ "male".
"Mother"'s Contribution: Z. "Father"'s Contribution: Y. "Host"'s Contribution: XY. Offspring's Result: XYYZ "male".
"Mother"'s Contribution: X. "Father"'s Contribution: Y. "Host"'s Contribution: ZZ. Offspring's Result: XYZZ "host".
"Mother"'s Contribution: X. "Father"'s Contribution: Z. "Host"'s Contribution: YZ. Offspring's Result: XYZZ "host".
"Mother"'s Contribution: Y. "Father"'s Contribution: X. "Host"'s Contribution: ZZ. Offspring's Result: XYZZ "host".
"Mother"'s Contribution: Y. "Father"'s Contribution: Z. "Host"'s Contribution: XZ. Offspring's Result: XYZZ "host".
"Mother"'s Contribution: Z. "Father"'s Contribution: X. "Host"'s Contribution: YZ. Offspring's Result: XYZZ "host".
"Mother"'s Contribution: Z. "Father"'s Contribution: Y. "Host"'s Contribution: XZ. Offspring's Result: XYZZ "host".
"Mother"'s Contribution: Z. "Father"'s Contribution: Z. "Host"'s Contribution: XY. Offspring's Result: XYZZ "host".
"Mother"'s Contribution: X. "Father"'s Contribution: X. "Host"'s Contribution: XY. Offspring's Result: XXXY non-viable.
"Mother"'s Contribution: X. "Father"'s Contribution: X. "Host"'s Contribution: XZ. Offspring's Result: XXXZ non-viable.
"Mother"'s Contribution: X. "Father"'s Contribution: X. "Host"'s Contribution: ZZ. Offspring's Result: XXZZ non-viable.
"Mother"'s Contribution: X. "Father"'s Contribution: Y. "Host"'s Contribution: XY. Offspring's Result: XXYY non-viable.
"Mother"'s Contribution: X. "Father"'s Contribution: Z. "Host"'s Contribution: XZ. Offspring's Result: XXZZ non-viable.
"Mother"'s Contribution: X. "Father"'s Contribution: Z. "Host"'s Contribution: ZZ. Offspring's Result: XZZZ non-viable.
"Mother"'s Contribution: Y. "Father"'s Contribution: X. "Host"'s Contribution: XY. Offspring's Result: XXYY non-viable.
"Mother"'s Contribution: Y. "Father"'s Contribution: Y. "Host"'s Contribution: XY. Offspring's Result: XYYY non-viable.
"Mother"'s Contribution: Y. "Father"'s Contribution: Y. "Host"'s Contribution: YZ. Offspring's Result: YYYZ non-viable.
"Mother"'s Contribution: Y. "Father"'s Contribution: Y. "Host"'s Contribution: ZZ. Offspring's Result: YYZZ non-viable.
"Mother"'s Contribution: Y. "Father"'s Contribution: Z. "Host"'s Contribution: YZ. Offspring's Result: YYZZ non-viable.
"Mother"'s Contribution: Y. "Father"'s Contribution: Z. "Host"'s Contribution: ZZ. Offspring's Result: YZZZ non-viable.
"Mother"'s Contribution: Z. "Father"'s Contribution: X. "Host"'s Contribution: XZ. Offspring's Result: XXZZ non-viable.
"Mother"'s Contribution: Z. "Father"'s Contribution: X. "Host"'s Contribution: ZZ. Offspring's Result: XZZZ non-viable.
"Mother"'s Contribution: Z. "Father"'s Contribution: Y. "Host"'s Contribution: YZ. Offspring's Result: YYZZ non-viable.
"Mother"'s Contribution: Z. "Father"'s Contribution: Y. "Host"'s Contribution: ZZ. Offspring's Result: YZZZ non-viable.
"Mother"'s Contribution: Z. "Father"'s Contribution: Z. "Host"'s Contribution: XZ. Offspring's Result: XZZZ non-viable.
"Mother"'s Contribution: Z. "Father"'s Contribution: Z. "Host"'s Contribution: YZ. Offspring's Result: YZZZ non-viable.
"Mother"'s Contribution: Z. "Father"'s Contribution: Z. "Host"'s Contribution: ZZ. Offspring's Result: ZZZZ non-viable.


If the "father" contributes two chromosomes, and both the "mother" and the "host" contribute one each;
"Mother"'s Contribution: X. "Father"'s Contribution: XY. "Host"'s Contribution: Z. Offspring's Result: XXYZ "female".
"Mother"'s Contribution: X. "Father"'s Contribution: XZ. "Host"'s Contribution: Y. Offspring's Result: XXYZ "female".
"Mother"'s Contribution: X. "Father"'s Contribution: YZ. "Host"'s Contribution: X. Offspring's Result: XXYZ "female".
"Mother"'s Contribution: Y. "Father"'s Contribution: XZ. "Host"'s Contribution: X. Offspring's Result: XXYZ "female".
"Mother"'s Contribution: Z. "Father"'s Contribution: XY. "Host"'s Contribution: X. Offspring's Result: XXYZ "female".
"Mother"'s Contribution: X. "Father"'s Contribution: YY. "Host"'s Contribution: Z. Offspring's Result: XYYZ "male".
"Mother"'s Contribution: X. "Father"'s Contribution: YZ. "Host"'s Contribution: Y. Offspring's Result: XYYZ "male".
"Mother"'s Contribution: Y. "Father"'s Contribution: XY. "Host"'s Contribution: Z. Offspring's Result: XYYZ "male".
"Mother"'s Contribution: Y. "Father"'s Contribution: XZ. "Host"'s Contribution: Y. Offspring's Result: XYYZ "male".
"Mother"'s Contribution: Y. "Father"'s Contribution: YZ. "Host"'s Contribution: X. Offspring's Result: XYYZ "male".
"Mother"'s Contribution: Z. "Father"'s Contribution: XY. "Host"'s Contribution: Y. Offspring's Result: XYYZ "male".
"Mother"'s Contribution: Z. "Father"'s Contribution: YY. "Host"'s Contribution: X. Offspring's Result: XYYZ "male".
"Mother"'s Contribution: X. "Father"'s Contribution: YZ. "Host"'s Contribution: Z. Offspring's Result: XYZZ "host".
"Mother"'s Contribution: Y. "Father"'s Contribution: XZ. "Host"'s Contribution: Z. Offspring's Result: XYZZ "host".
"Mother"'s Contribution: Z. "Father"'s Contribution: XY. "Host"'s Contribution: Z. Offspring's Result: XYZZ "host".
"Mother"'s Contribution: Z. "Father"'s Contribution: XZ. "Host"'s Contribution: Y. Offspring's Result: XYZZ "host".
"Mother"'s Contribution: Z. "Father"'s Contribution: YZ. "Host"'s Contribution: X. Offspring's Result: XYZZ "host".
"Mother"'s Contribution: X. "Father"'s Contribution: XY. "Host"'s Contribution: X. Offspring's Result: XXXY non-viable.
"Mother"'s Contribution: X. "Father"'s Contribution: XY. "Host"'s Contribution: Y. Offspring's Result: XXYY non-viable.
"Mother"'s Contribution: X. "Father"'s Contribution: XZ. "Host"'s Contribution: X. Offspring's Result: XXXZ non-viable.
"Mother"'s Contribution: X. "Father"'s Contribution: XZ. "Host"'s Contribution: Z. Offspring's Result: XXZZ non-viable.
"Mother"'s Contribution: X. "Father"'s Contribution: YY. "Host"'s Contribution: X. Offspring's Result: XXYY non-viable.
"Mother"'s Contribution: X. "Father"'s Contribution: YY. "Host"'s Contribution: Y. Offspring's Result: XYYY non-viable.
"Mother"'s Contribution: Y. "Father"'s Contribution: XY. "Host"'s Contribution: X. Offspring's Result: XXYY non-viable.
"Mother"'s Contribution: Y. "Father"'s Contribution: XY. "Host"'s Contribution: Y. Offspring's Result: XYYY non-viable.
"Mother"'s Contribution: Y. "Father"'s Contribution: YY. "Host"'s Contribution: X. Offspring's Result: XYYY non-viable.
"Mother"'s Contribution: Y. "Father"'s Contribution: YY. "Host"'s Contribution: Y. Offspring's Result: YYYY non-viable.
"Mother"'s Contribution: Y. "Father"'s Contribution: YY. "Host"'s Contribution: Z. Offspring's Result: YYYZ non-viable.
"Mother"'s Contribution: Y. "Father"'s Contribution: YZ. "Host"'s Contribution: Y. Offspring's Result: YYYZ non-viable.
"Mother"'s Contribution: Y. "Father"'s Contribution: YZ. "Host"'s Contribution: Z. Offspring's Result: YYZZ non-viable.
"Mother"'s Contribution: Z. "Father"'s Contribution: XZ. "Host"'s Contribution: X. Offspring's Result: XXZZ non-viable.
"Mother"'s Contribution: Z. "Father"'s Contribution: XZ. "Host"'s Contribution: Z. Offspring's Result: XZZZ non-viable.
"Mother"'s Contribution: Z. "Father"'s Contribution: YY. "Host"'s Contribution: Y. Offspring's Result: YYYZ non-viable.
"Mother"'s Contribution: Z. "Father"'s Contribution: YY. "Host"'s Contribution: Z. Offspring's Result: YYZZ non-viable.
"Mother"'s Contribution: Z. "Father"'s Contribution: YZ. "Host"'s Contribution: Y. Offspring's Result: YYZZ non-viable.
"Mother"'s Contribution: Z. "Father"'s Contribution: YZ. "Host"'s Contribution: Z. Offspring's Result: YZZZ non-viable.

If the "mother" contributes two chromosomes, and both the "father" and the "host" contribute one each;
"Mother"'s Contribution: XX. "Father"'s Contribution: Y. "Host"'s Contribution: Z. Offspring's Result: XXYZ "female".
"Mother"'s Contribution: XX. "Father"'s Contribution: Z. "Host"'s Contribution: Y. Offspring's Result: XXYZ "female".
"Mother"'s Contribution: XY. "Father"'s Contribution: X. "Host"'s Contribution: Z. Offspring's Result: XXYZ "female".
"Mother"'s Contribution: XY. "Father"'s Contribution: Z. "Host"'s Contribution: X. Offspring's Result: XXYZ "female".
"Mother"'s Contribution: XZ. "Father"'s Contribution: X. "Host"'s Contribution: Y. Offspring's Result: XXYZ "female".
"Mother"'s Contribution: XZ. "Father"'s Contribution: Y. "Host"'s Contribution: X. Offspring's Result: XXYZ "female".
"Mother"'s Contribution: YZ. "Father"'s Contribution: X. "Host"'s Contribution: X. Offspring's Result: XXYZ "female".
"Mother"'s Contribution: XY. "Father"'s Contribution: Y. "Host"'s Contribution: Z. Offspring's Result: XYYZ "male".
"Mother"'s Contribution: XY. "Father"'s Contribution: Z. "Host"'s Contribution: Y. Offspring's Result: XYYZ "male".
"Mother"'s Contribution: XZ. "Father"'s Contribution: Y. "Host"'s Contribution: Y. Offspring's Result: XYYZ "male".
"Mother"'s Contribution: YZ. "Father"'s Contribution: X. "Host"'s Contribution: Y. Offspring's Result: XYYZ "male".
"Mother"'s Contribution: YZ. "Father"'s Contribution: Y. "Host"'s Contribution: X. Offspring's Result: XYYZ "male".
"Mother"'s Contribution: XY. "Father"'s Contribution: Z. "Host"'s Contribution: Z. Offspring's Result: XYZZ "host".
"Mother"'s Contribution: XZ. "Father"'s Contribution: Y. "Host"'s Contribution: Z. Offspring's Result: XYZZ "host".
"Mother"'s Contribution: XZ. "Father"'s Contribution: Z. "Host"'s Contribution: Y. Offspring's Result: XYZZ "host".
"Mother"'s Contribution: YZ. "Father"'s Contribution: X. "Host"'s Contribution: Z. Offspring's Result: XYZZ "host".
"Mother"'s Contribution: YZ. "Father"'s Contribution: Z. "Host"'s Contribution: X. Offspring's Result: XYZZ "host".
"Mother"'s Contribution: XX. "Father"'s Contribution: X. "Host"'s Contribution: X. Offspring's Result: XXXX non-viable.
"Mother"'s Contribution: XX. "Father"'s Contribution: X. "Host"'s Contribution: Y. Offspring's Result: XXXY non-viable.
"Mother"'s Contribution: XX. "Father"'s Contribution: X. "Host"'s Contribution: Z. Offspring's Result: XXXZ non-viable.
"Mother"'s Contribution: XX. "Father"'s Contribution: Y. "Host"'s Contribution: X. Offspring's Result: XXXY non-viable.
"Mother"'s Contribution: XX. "Father"'s Contribution: Y. "Host"'s Contribution: Y. Offspring's Result: XXYY non-viable.
"Mother"'s Contribution: XX. "Father"'s Contribution: Z. "Host"'s Contribution: X. Offspring's Result: XXXZ non-viable.
"Mother"'s Contribution: XX. "Father"'s Contribution: Z. "Host"'s Contribution: Z. Offspring's Result: XXZZ non-viable.
"Mother"'s Contribution: XY. "Father"'s Contribution: X. "Host"'s Contribution: X. Offspring's Result: XXXY non-viable.
"Mother"'s Contribution: XY. "Father"'s Contribution: X. "Host"'s Contribution: Y. Offspring's Result: XXYY non-viable.
"Mother"'s Contribution: XY. "Father"'s Contribution: Y. "Host"'s Contribution: X. Offspring's Result: XXYY non-viable.
"Mother"'s Contribution: XY. "Father"'s Contribution: Y. "Host"'s Contribution: Y. Offspring's Result: XYYY non-viable.
"Mother"'s Contribution: XZ. "Father"'s Contribution: X. "Host"'s Contribution: X. Offspring's Result: XXXZ non-viable.
"Mother"'s Contribution: XZ. "Father"'s Contribution: X. "Host"'s Contribution: Z. Offspring's Result: XXZZ non-viable.
"Mother"'s Contribution: XZ. "Father"'s Contribution: Z. "Host"'s Contribution: X. Offspring's Result: XXZZ non-viable.
"Mother"'s Contribution: XZ. "Father"'s Contribution: Z. "Host"'s Contribution: Z. Offspring's Result: XZZZ non-viable.
"Mother"'s Contribution: YZ. "Father"'s Contribution: Y. "Host"'s Contribution: Y. Offspring's Result: YYYZ non-viable.
"Mother"'s Contribution: YZ. "Father"'s Contribution: Y. "Host"'s Contribution: Z. Offspring's Result: YYZZ non-viable.
"Mother"'s Contribution: YZ. "Father"'s Contribution: Z. "Host"'s Contribution: Y. Offspring's Result: YYZZ non-viable.
"Mother"'s Contribution: YZ. "Father"'s Contribution: Z. "Host"'s Contribution: Z. Offspring's Result: YZZZ non-viable.

I'm sure everyone who reads this post can see why I think this system of kyonides's would be complicated.

Posted November 11th, 2008 by chiarizio

I think that it could add an interesting social dynamic if part of the population of this species were to reproduce completely pathogenically, as only one parent would be necessary to produce the two sexually reproducing sexes, and also an individual of the species would learn more about their sex/gender roles from their grandparents than their parents. Also, if the only individual left were neutrois, they could (possibly) repopulate an area by themself.

If you chose this option, you may want to ask yourself why one parent could still produce two sexes if the species only needs one sex to reproduce. What's the use of a second sex if they can reproduce asexually, anyway? Yeah, it would be more evolutionarily beneficial but it would also be more inefficient I would think. Would either of these sexes be able to reproduce sexually, or would one be parthenogenic (<- that is the right spelling) like its parent?

Because the neutrois would be AB (or WZ or XY or whatever you'd prefer to term it) and parthogenesis always makes individuals with two copies of each series of chromosomes. All children produced this way would either be AA or BB, ie either "males" or "females". Similarly, if the neutrois who was their parent was heterozygous for some trait (for example Purple skin but having a purple skin gene and a blue skin gene), all their children would either be homozygous Purple, or homozygous blue.
I already stated that males and females would reproduce sexually.
I do not want this world to follow Earth biology exactly, so there is no need for one sex allele to be mandatory for a fetus to be viable, and I've decided that the sex alleles would be codominant for this species.
Actually, it would be extremely like most sexually-reproducing Earth species, to have three sexes; monoploid males and females who reproduce only sexually and whose children are all always diploid; and diploid "neuters" who reproduce parthenogenetically and whose children are all always monoploid, either males or females.

-------------------------------------------------------------------------------------

About the advantages of polyploidy (such as triploidy and tetraploidy):

"Hybrid vigor" is a common thing on Earth. A specimen which is heterozygous at a particular locus is often better-adapted than one which is homozygous for either allele. Sometimes one allele at a locus produces one protein that confers an advantage, and a different allele at the same locus produces a different protein that confers a slightly different advantage; neither protein confers the advantage the other protein confers.

So, homozygous specimens, that have two copies of the same allele at that locus, get only one of these advantages, not both; but heterozygous specimens, with one copy of each of those alleles, get both.

Well, fine, but, what if there are three alleles that could fit on that locus?

A diploid specimen has only two versions of that locus, so it could only have copies of at most two of the alleles.

But if the specimens were triploid, they could get a copy of each of the three alleles. This could give them even more hybrid vigor than the diploid hybrids have.

Also; even if there are only two alleles:

Consider what if the alleles are equally common.

Among diploids, 25% would have two copies of one allele, 25% would have two copies of the other, and 50% would be heterozygous. Only 50% would benefit from "hybrid vigor".

But among triploids, 12.5% would be homozygous for the first allele, 12.5% would be homozygous for the second, 37.5% would have two copies of the first allele and one copy of the second, and 37.5% would have two copies of the second allele and one copy of the first. So 75% would benefit from "hybrid vigor".

I don't know under what circumstances these advantages of polyploidy would cause it to evolve; but such circumstances may be imaginable.

Posted November 11th, 2008 by chiarizio

Actually, it would be extremely like most sexually-reproducing Earth species, to have three sexes; monoploid males and females who reproduce only sexually and whose children are all always diploid; and diploid "neuters" who reproduce parthenogenetically and whose children are all always monoploid, either males or females.


That would be analogous to having females be X, males being Y and neutrois being XY, which is not what I want. I don't want males and females to be monoploid. I want all three genders to be diploid.

Posted November 11th, 2008 by bloodb4roses

I have thought of a system where there are four sexes (A B C D)

A and B creates a D
B and C creates an A
C and D creates a B
D and A creates a C

A is not fertile with C
B is not fertile with D

In this system, you could have two carriers (A and C) and two fertilizers (B and D). Now how would this work, I still have no idea. Also, why would they have two of a kind is a mystery.

Posted November 11th, 2008 by Yiuel
Yiuel
 

I think that it could add an interesting social dynamic if part of the population of this species were to reproduce completely pathogenically, as only one parent would be necessary to produce the two sexually reproducing sexes, and also an individual of the species would learn more about their sex/gender roles from their grandparents than their parents. Also, if the only individual left were neutrois, they could (possibly) repopulate an area by themself.


If you chose this option, you may want to ask yourself why one parent could still produce two sexes if the species only needs one sex to reproduce. What's the use of a second sex if they can reproduce asexually, anyway? Yeah, it would be more evolutionarily beneficial but it would also be more inefficient I would think. Would either of these sexes be able to reproduce sexually, or would one be parthenogenic (<- that is the right spelling) like its parent?


Because the neutrois would be AB (or WZ or XY or whatever you'd prefer to term it) and parthogenesis always makes individuals with two copies of each series of chromosomes. All children produced this way would either be AA or BB, ie either "males" or "females".


Wouldn't the parent also be able to produce an AB individual if they had an AB set themselves? I know parthenogenesis can only make clones of the parent but, With a parthenogenic hermaphrodite, you can create individuals with any arrangement of what you already have since hermaphrodites have characteristics of both sexes. You're going with three sexes instead of just two so hermaphrodites would also have their own unique chromosome set. From what I know, parthenogenic organisms on Earth are either single-sex monoploid - in which case you're stuck with only one chromosome no matter what you do - or diploid sexually reproducing organism that use parthenogenesis as an alternative solution. Like many (or all?) monitor lizard species. However, since the sex which produces the offspring is always female and hence only has an XX combination, she can only produce more females. Neither are hermaphrodites by their species' standard so they can't produce more than one sex. If your species standard includes hermaphrodites as a third sex, they should be able to produce three sexes on their own.

And those born with AA or BB could rely on sexual reproduction to create the same three genders, I guess. But then my initial question comes up again.


On the other hand, if the neutrois reproduced sexually with each other, it would be evolutionarily beneficial by mixing more of the genetics in each generation, making them more resistant against deseases and parasites.


Sort of like hermaphrodites, then? I like this idea better. It fits in better with the two-sex system. I mean, you could see how something like this could appear in a once two-sex species.


Actually, I think I want this planet to have creatures that often have three sexes. Having one or two wouldn't be unheard of, but the majority of species would have three.


You could still have three sexes with sexually-reproducing hermaphrodites if all three chromosome combinations were viable. There is a strong chance one or both of the other sexes would get weeded out though, as I suggested above. Moreso if the hermaphrodites could reproduce sexually.

a third chromosome, let's say it's Z, instead?
The chromosomes would be distributed like this:
Male - 50% Y, 25% X, 25% Z
Female - 50% X, 25% Y, 25% Z
Host - 50% Z, 25% X, 25% Y


That's reasonable for a [tetra


"Tri-" = three, "tetra-" = four.


I wrote "tetraploid" because XYZZ, XYYZ, and XXYZ are all sets of four sex-chromosomes.

It was the XXYZ - XYYZ - XYZZ system that I meant was "reasonable for tetraploid species".


But that's the thing. From reading kyonides' post, I can't see where he said anything about four genders or four chromosomes. Furthermore, I don't know why you put four chromosomes in each set. You can't even get more than three varients with the four-chromosome sets that you've already got. So, if you do know that tetra- means "four," what does four hav to do with any of it?

A guess: the 50% may not necessarily mean that an extra chromosome is added. Maybe he's using a punnett square with nine boxes or something else. Just don't doubt me until you ask him or wait until he responds.

Actually, it would be extremely like most sexually-reproducing Earth species, to have three sexes; monoploid males and females who reproduce only sexually and whose children are all always diploid; and diploid "neuters" who reproduce parthenogenetically and whose children are all always monoploid, either males or females.


That would be analogous to having females be X, males being Y and neutrois being XY, which is not what I want. I don't want males and females to be monoploid. I want all three genders to be diploid.


But if your species has a viability issue with the YY combination the way most Earth animals do, I don't think that would be possible. On Earth, YY sets aren't viable because you need atleast one X for normal development. If your three-sex species doesn't have this issue, I say go for it...only, with a monoploidy system for males and females, it may be even more likely for these two sexes to get weeded out since a punnett square gives you 50% for hermaphrodites and only 25% for the other two sexes. It would be cool to have parthenogenesis be the rule for a diploid species though, and sexual reproduction be the the exception instead of the other way around as on Earth.

Posted November 11th, 2008 by Cerne
Cerne
 


Wouldn't the parent also be able to produce an AB individual if they had an AB set themselves? I know parthenogenesis can only make clones of the parent but, With a parthenogenic hermaphrodite, you can create individuals with any arrangement of what you already have since hermaphrodites have characteristics of both sexes.


Actually, that's only true if the parent is already homozygous for all it's traits. There is a type of lizard on Earth that reproduces (generally) through parthenogenesis, but is closely related to a species of lizards that reproduce sexually. If a male of the sexual species mates with a member of the parthenogenic species, which is rare but possible, the resulting female offspring will usually be parthenogenic, but heterozygous for some traits. For those traits, the children of the crossbreed will be homozygous for those traits instead.

Also, komodo dragon females can reproduce parthenogenically, but because komodos females are ZW, they will only produce ZZ male offspring, not females.

You're going with three sexes instead of just two so hermaphrodites would also have their own unique chromosome set. From what I know, parthenogenic organisms on Earth are either single-sex monoploid - in which case you're stuck with only one chromosome no matter what you do - or diploid sexually reproducing organism that use parthenogenesis as an alternative solution. Like many (or all?) monitor lizard species. However, since the sex which produces the offspring is always female and hence only has an XX combination, she can only produce more females. Neither are hermaphrodites by their species' standard so they can't produce more than one sex. If your species standard includes hermaphrodites as a third sex, they should be able to produce three sexes on their own.


Not parthenogenically, as they would only be reduplicating one "set" of chromosomes to have a full set.


[quote="bloodb4roses"]

On the other hand, if the neutrois reproduced sexually with each other, it would be evolutionarily beneficial by mixing more of the genetics in each generation, making them more resistant against deseases and parasites.


Sort of like hermaphrodites, then? I like this idea better. It fits in better with the two-sex system. I mean, you could see how something like this could appear in a once two-sex species.


Actually, I think I want this planet to have creatures that often have three sexes. Having one or two wouldn't be unheard of, but the majority of species would have three.


You could still have three sexes with sexually-reproducing hermaphrodites if all three chromosome combinations were viable. There is a strong chance one or both of the other sexes would get weeded out though, as I suggested above. Moreso if the hermaphrodites could reproduce sexually.


It would be likely that only hermaphrodites would be left, since the males and females would be so much rarer statistically speaking....

Actually, it would be extremely like most sexually-reproducing Earth species, to have three sexes; monoploid males and females who reproduce only sexually and whose children are all always diploid; and diploid "neuters" who reproduce parthenogenetically and whose children are all always monoploid, either males or females.


That would be analogous to having females be X, males being Y and neutrois being XY, which is not what I want. I don't want males and females to be monoploid. I want all three genders to be diploid.


But if your species has a viability issue with the YY combination the way most Earth animals do, I don't think that would be possible. On Earth, YY sets aren't viable because you need atleast one X for normal development. If your three-sex species doesn't have this issue, I say go for it...only, with a monoploidy system for males and females, it may be even more likely for these two sexes to get weeded out since a punnett square gives you 50% for hermaphrodites and only 25% for the other two sexes. It would be cool to have parthenogenesis be the rule for a diploid species though, and sexual reproduction be the the exception instead of the other way around as on Earth.


There is no reason in my view that YY in this world would unviable, though I may change it to be AA, BB and AB for the three sexes, so it's less confusing for people familiar with Earth's genetics. And as stated several times, which you may look up and confirm on you own, parthenogenesis does NOT "clone" the parent, but instead produces individuals that are homozygous for all traits, independent of whether the mother was as well.

Posted November 12th, 2008 by bloodb4roses

Your plants could just grow the animals in them. Mammals are only warm blooded as a means to maintain a higher rate of metabolism and more efficient muscles. Sure, we've grown adapted to it, but there's no fundamental reason that it can't be turned off and on- hibernation case in point.

Your plants could grow cold blooded fetuses, which warm up once born.


Not necessarily. Birds have to keep their eggs warm. Why don't they just evolve the ability to turn off their warm-bloodedness? It'd be advantageous. With hibernation, the animal isn't doing anything. It's not as if they're functioning like a reptile, they're barely functioning. Whereas an embryo is definitely doing something---developing.
It's not that I can't imagine an alien biology in which cold-blooded infants grow into warm-blooded adults. It's just that, considering what we have here on earth, I think arguing that warm-bloodedness is a good reason for live birth is perfectly valid. And in the end, I like my system and want excuses for it rather than ways to avoid using it.

Posted November 12th, 2008 by lryda mbazha

But that's the thing. From reading kyonides' post, I can't see where he said anything about four genders or four chromosomes. Furthermore, I don't know why you put four chromosomes in each set. You can't even get more than three varients with the four-chromosome sets that you've already got. So, if you do know that tetra- means "four," what does four have to do with any of it?
It's just that the most obvious way to have:

50% X, 25% Y, 25% Z
and
25% X, 50% Y, 25% Z
and
50% X, 25% Y, 50% Z

is XXYZ and XYYZ and XYZZ.

You're right, Kyonides said there'd be three sexes and three parents per specimen.

My problem was; I don't see how that can be done efficiently; it looks like there'd be so much wastage that it would be selected against. (That is, a three-parent three-sex system with XXYZ, XYYZ, and XYZZ as the sexes.)

A guess: the 50% may not necessarily mean that an extra chromosome is added. Maybe he's using a punnett square with nine boxes or something else. Just don't doubt me until you ask him or wait until he responds.
I know I hadn't thought of that because I don't understand it.

@Kyonides, it looks like Cerne and I are waiting for you.

How would a nine-box Punnett square make that work?

Or how would it work?

-------------------------------------------------------------------------------------

Remember that, among other things, to be stable, the system has to produce equal numbers of each sex; because in any generation with unbalanced sex-ratio, a parent with more children of the rarer sex, will have more grandchildren (on average and all other things being equal) than a parent with fewer children of the rarer sex and more children of the more common sex.

So there will be "selective pressure" towards a balanced sex-ratio.

(Of course, that applies to offspring at the time of mating. If life is such that 90% of the males die before adulthood but only 1% of the females do, then the selective pressure will be towards having about 9.9 sons per daughter.)

Posted November 12th, 2008 by chiarizio


Not necessarily. Birds have to keep their eggs warm.


Not all of them, it's just overwhelmingly more efficient for embryo development.

If you look into reptile egg incubation, you'll find that most, too, need to be heated; this is why most reptiles thrive in warmer climates.

There's not really any sharp line between cold and warm blooded animals, or those that lay eggs or have live births- it's all a matter of degree.

Why don't they just evolve the ability to turn off their warm-bloodedness?


Because then it would take a very long time for the eggs to finish developing and hatching, and they would, as such, be more susceptible from threats not only from being eaten by larger animals, but by bacteria seeking to pierce the membrane into the sterile egg, and the mother would have to invest more resources into the egg itself to offset this.

It's just that, considering what we have here on earth, I think arguing that warm-bloodedness is a good reason for live birth is perfectly valid.


It's more that: If you're going to have a cooperative heat source anyway, you might as well use it to help ensure survival of the embryos.

Take insects as an example, even as small as they are, being so cold it takes them an extremely long time to develop- thus the larval stage. The helpless egg can reach a slightly less helpless larval stage where it can kick on its metabolism, which is essential for complete development (since the final form, in order to be functional, is quite a bit larger).


The thing I think you're missing, though, is that a tree, as per this biology, is significantly different from an egg. Such a tree would be large, providing an inherent degree of protection from predation and the elements. The fetus inside could afford to take its time.

In cases where the tree is larger and stronger than the organism, it's to the fetus' advantage to develop in the plant form rather than in the animal form, even if it takes longer (and it's to the animal's advantage too- it doesn't have to carry around a fetus; pregnancy can be a substantial encumbrance, especially to animals giving birth to live young of significant maturity- the extra weight doesn't bother a tree, which is also more stable- no sloshing around).

The likelihood of more than two states developing is slim in itself, but when it may even go against a potential evolutionary advantage...

And in the end, I like my system and want excuses for it rather than ways to avoid using it.


That's fine, I'm just giving you my best evaluation of what is likely- the style of a conworld always comes first.

Personally, I think a live birth of crawling out of a tree seems pretty cool. I could imagine a community of small people building up among a grove of large trees, wherein each tree is the child bearer for a family.

Posted November 12th, 2008 by Blake
Blake
 

In cases where the tree is larger and stronger than the organism, it's to the fetus' advantage to develop in the plant form rather than in the animal form

First of all, I'm not sure this group comes from trees. I was thinking sprawling vines or low shrubs. Making it difficult for the plantlike form to provide the nutrients and protection necessary for extended incubation---especially when you factor in the reduced efficiency of development the lower temperature would create. Also, these things developed endothermy to deal with increasingly cold climates, so cold-bloodedness wasn't a great strategy in general right then. And cold adaptations often mean increased size for mammals, while cold=dry=smaller plants. So maybe the animal-like form got bigger and the plant-like one couldn't keep up, while simultaneously warm blood got very useful and unheated embryonic development got even slower and less efficient. Obviously I'll need to have intermediate steps to make the evolution of the altered life-cycle plausible, but still. I think it could happen.

And finally, your arguments are biased by asthetic considerations, like mine. You like the idea of tree-born people, I like the idea of feuds between tribes arising over who has the right to get impregnated by which shrub. If it gives you any satisfaction, something vaguely endothermic and long-developing can come straight out of trees.

And thanks for caring enough to argue with me about it. :)

Posted November 12th, 2008 by lryda mbazha

Okay, here's my idea.

There are three genders, let's call them Male (AA), Hermaphrodite (AB) and Female (BB).

  • Any gender can get pregnant. Males and Females have eggs with a single chromosome, A for males and B for females.

  • Hermaphrodites naturally secrete a special enzyme that begins the fertilization process. They must mate with a male or female in order for them to begin fertilization, although such mating does not carry genetic material. Because hermaphrodites naturally secrete the enzyme, they are the only ones capable of mating with themselves, although they can mate with another hermaphrodite and fertilize one another (again without transferring any genetic material).

  • For a period of, say, two months, a male or female egg can be further fertilized. Both males and females secrete something sperm-like which again has one chromosome, A for males and B for females. Gender crossing is possible, as is self-fertilization (although pointless and rather hard to do).

  • At the end of that two months, if the egg is not fertilized, its chromosomes double themselves and the new child becomes a clone of the parent.

  • Hermaphrodite eggs are fully fertilized and do not have a two-month "waiting period". Their children are clones, with whatever genetic abnormalities are caused by mutation.

    Conclusions to reach

    1. All three genders would be genetically very seperate from one another, as their lines continue through essentially asexual reproduction.

    2. However, newly born hermaphrodites would be a hybrid of two of those genders, and unlike the other hermaphroditic lines.

  • Posted November 13th, 2008 by Xhin
    Xhin
    Nature is beautiful

    I have thought of a way a triploid three-parent three-sex species could use the X-Y-Z sex-chromosomes.

    Suppose:

    Everyone with at least one Z chromosome is a "Host".
    Everyone with no Z chromosome, but with at least one Y chromosome, is a "Male".
    Everyone with neither any Z chromosomes nor any Y chromosomes is a "Female".

    Everyone has three parents; a "Host", a male "Father", and a female "Mother".

    Obviously everyone will have to have at least one X chromosome.

    In order for females to be conceived at all, it must be possible for each parent to have at least one X chromosome, since females are XXX and have to get one chromosme from each parent.

    But, also, everyone has a mother, and the only kind of sex-chromosome she could contribute would be an X.

    Also, nobody can have more than one Z chromosome.

    Everybody has exactly one "Host" parent, who can contribute exactly one chromosome; and everyone with a Z chromosome is a "Host"; so you can't get a Z chromosome from your mother or your father, only from your "Host"; so you can't get more than one Z chromosome.

    So;
    Females come in one genotype (as far as sex-chromosomes are concerned): XXX.
    Males come in two genotypes (as far as sex-chromosomes are concerned): XXY and XYY.
    Hosts come in two genotypes (as far as sex-chromosomes are concerned): XXZ and XYZ.

    (Note that Hosts have to get their Z chromosome from their Host parent. But Males could get a Y chromosome from their Father, or, if their Host parent happens to be XYZ, from their Host parent; or both, and turn out to be XYY males.)

    For this system to be "stable" (in the sense that a pencil balanced on its point is "stable"), ([EDIT]: I meant "at equilibrium". [/EDIT]) we need the fraction of Hosts who are XXZ to be the golden ration phi = (root(5)-1)/2, and the fraction of Males who are XXY to be 3*phi-1.
    That is: about 61.8% of Hosts are XXZ and about 38.2% of Hosts are XYZ;
    and about 85.41% of Males are XXY and about 14.59% of Males are XYY.

    I do not yet know whether this system is "stable" in the sense that a three-legged stool standing on a flat floor is "stable". I have not worked out yet whether small perturbations from the above "stable" system will tend to shrink or to grow or to just remain.

    Does anyone else want to?

    Posted November 13th, 2008 by chiarizio


  • At the end of that two months, if the egg is not fertilized, its chromosomes double themselves and the new child becomes a clone of the parent.

  • Hermaphrodite eggs are fully fertilized and do not have a two-month "waiting period". Their children are clones, with whatever genetic abnormalities are caused by mutation.


  • So, these beings are always homozygous for every single allele? Here's an example:

    If these beings have two chromosomes (the sex chromosome and another) and are homozygous for all genes (let's say our individual is BB and also has the alleles CC, dd and ee), then yes their offspring would be clones as they would get one of each gene (B, C, d, and e) which would then be doubled (BB, CC, dd, ee).

    But if they were heterozygous for anything (let's assume they are Cc instead), then their offspring will not be clones, because statistically half the offspring would receive the dominant allele (C) which would get doubled (offspring would be BB, CC, dd, ee) and half the recessive allele (c) which again would get doubled (offspring would be BB, cc, dd, ee). In the latter case, not even the phenotype would be the same.

    Since there could be genetic mutations that could be passed to offspring but not show up in the parent, not all offspring would be clones, even if they reproduced completely assexually. And hermaphrodites would not produce AB children.

    Posted November 13th, 2008 by bloodb4roses


    Wouldn't the parent also be able to produce an AB individual if they had an AB set themselves? I know parthenogenesis can only make clones of the parent but, With a parthenogenic hermaphrodite, you can create individuals with any arrangement of what you already have since hermaphrodites have characteristics of both sexes.


    Actually, that's only true if the parent is already homozygous for all it's traits.


    ...why? If AB isn't heterozygous, it should also be duplicated. And you said that you were going to have an exclusively parthenogenic sex/population so they'll be homozygous anyway.

    You're going with three sexes instead of just two so hermaphrodites would also have their own unique chromosome set. From what I know, parthenogenic organisms on Earth are either single-sex monoploid - in which case you're stuck with only one chromosome no matter what you do - or diploid sexually reproducing organism that use parthenogenesis as an alternative solution. Like many (or all?) monitor lizard species. However, since the sex which produces the offspring is always female and hence only has an XX combination, she can only produce more females. Neither are hermaphrodites by their species' standard so they can't produce more than one sex. If your species standard includes hermaphrodites as a third sex, they should be able to produce three sexes on their own.


    Not parthenogenically, as they would only be reduplicating one "set" of chromosomes to have a full set.


    And which "set" would that be? What is your species' standard chromosome? For humans, the standard or default is the X chromosome. If your species is the same, each individual born from a hermaphrodite will be female. Following your first idea, you now have one sex entorely made up of females. If they hadn't speciated by then, the females would be re-absorbed into the two-sex population. Unless the hermaphrodites can also produce males by duplicating the male chromosome, it looks now like the parthenogenesis idea might be a no-win for three genders. If it can, though, one thing you could do is have an alternation between male-female sexual reproduction and hermaphrodite parthenogenesis. Males could produce the male chromosome exclusively and females could produce the female chromosome exclusively. Once these two chromosomes come together, they produce an AB combination which produces a hermaphrodite. The hermaphrodite then parthenogenically duplicates either A or B, meaning it sometimes produces males and sometimes produces females. Would this work?

    There is no reason in my view that YY in this world would unviable,


    Apparently in humans the Y chromosome has no actual genetic information on it. The only function it has is to turn females into males so a YY combination would lead to inviability (I.e. nothing will develop). I learned this from my second year bio-anthropology class but the only source of information I could find that directly supports it is this site.

    The human Y chromosome is a smidgen of a chromosome and contains virtually no
    genes. It only contains those genes necessary for becoming male, the SRY for
    example. Sex determination occurs differently in different species and I
    cannot say whether all Y chromosomes are so small in all species. But in
    humans, the X contains genes that all of need for life-in females there are
    two copies of each gene and in males only one (they only have one X) but most
    of the genes on the X have nothing to do with sex determination. Examples
    include genes for the ability to see color and to make blood clotting
    proteins. Whether these same genes are found on all species' X I do not
    know,
    but I suspect not all of them. So, at least in humans, everyone needs at
    least one X. Without one, life is impossible (for humans).

    vanhoeck


    And as stated several times, which you may look up and confirm on you own, parthenogenesis does NOT "clone" the parent, but instead produces individuals that are homozygous for all traits, independent of whether the mother was as well.


    Eventually, if offspring were parthenogenically produced over several generations, they would be. Through parthenogenesis, homozygous individual can not produce heterozygous offspring (as I think you already said). Neither can they produce offspring with recessive traits if they are homozygous dominant, and vice versa. In your first scenario, if you had a part of the species' population which reproduced completely parthenogenically, after a while they would essentially be producing clones of themselves. And they would probably all die out shortly after.

    It's just that the most obvious way to have:

    50% X, 25% Y, 25% Z
    and
    25% X, 50% Y, 25% Z
    and
    50% X, 25% Y, 50% Z

    is XXYZ and XYYZ and XYZZ.


    I assumed as much. Maybe it has something to do with the chance that a chromosome will show up.

    You're right, Kyonides said there'd be three sexes and three parents per specimen.


    That seems to be the problem with a three-sex triploid species. You can't really have more of one chromosome than any of the others without taking atleast one away. And I'm willing to bet it's like that for every sexually reproducing organism where the number of fertile sexes (and hence chromosomes) matches the number of chromosomes allowed per set.

    Suppose:

    Everyone with at least one Z chromosome is a "Host".
    Everyone with no Z chromosome, but with at least one Y chromosome, is a "Male".
    Everyone with neither any Z chromosomes nor any Y chromosomes is a "Female".

    Everyone has three parents; a "Host", a male "Father", and a female "Mother".

    Obviously everyone will have to have at least one X chromosome.

    In order for females to be conceived at all, it must be possible for each parent to have at least one X chromosome, since females are XXX and have to get one chromosme from each parent.

    But, also, everyone has a mother, and the only kind of sex-chromosome she could contribute would be an X.

    Also, nobody can have more than one Z chromosome.

    Everybody has exactly one "Host" parent, who can contribute exactly one chromosome; and everyone with a Z chromosome is a "Host"; so you can't get a Z chromosome from your mother or your father, only from your "Host"; so you can't get more than one Z chromosome.


    Or why don't we assume that every female delivers a default X chromosome while males have the option of producing an X or Y and hosts have the option of producing all three? That way any sex with all X's will be female, any sex with one or twp Y chromosomes will be male, and any sex with a single Z chromosome will be a host? Statistically, that brings us to (I think) 15% female, 50% male, and 35% host. Better yet, we can have three viable sexes, three parents, and three chromosomes per individual.

    Sorry to say but, since I only wanted two parents for my species and one sex to be infertile, it looks like I'll have to avoid this system and have my species remain diploid. A three-parent system just doesn't sound very efficient to me... But by all means, somebody else can use it if they want to. My thanks go out to both kyonides and chiarizio for their generous assistance and lots of good quality information :thumbleft:

    I do not yet know whether this system is "stable" in the sense that a three-legged stool standing on a flat floor is "stable". I have not worked out yet whether small perturbations from the above "stable" system will tend to shrink or to grow or to just remain.

    Does anyone else want to?


    Not me. Too many numbers :shock:

    Posted November 14th, 2008 by Cerne
    Cerne
     


    ...why? If AB isn't heterozygous, it should also be duplicated. And you said that you were going to have an exclusively parthenogenic sex/population so they'll be homozygous anyway.


    AB is heterozygous, having one A allele and one B allele.


    And which "set" would that be? What is your species' standard chromosome? For humans, the standard or default is the X chromosome. If your species is the same, each individual born from a hermaphrodite will be female. Following your first idea, you now have one sex entorely made up of females. If they hadn't speciated by then, the females would be re-absorbed into the two-sex population. Unless the hermaphrodites can also produce males by duplicating the male chromosome, it looks now like the parthenogenesis idea might be a no-win for three genders. If it can, though, one thing you could do is have an alternation between male-female sexual reproduction and hermaphrodite parthenogenesis.


    To quote MSat: Hurrrr...

    Males could produce the male chromosome exclusively and females could produce the female chromosome exclusively. Once these two chromosomes come together, they produce an AB combination which produces a hermaphrodite. The hermaphrodite then parthenogenically duplicates either A or B, meaning it sometimes produces males and sometimes produces females. Would this work?


    That's basically what I've been explaining all this time...

    Apparently in humans the Y chromosome has no actual genetic information on it. The only function it has is to turn females into males so a YY combination would lead to inviability (I.e. nothing will develop). I learned this from my second year bio-anthropology class but the only source of information I could find that directly supports it is this site.


    And again, "for humans". I'm not asking if this would work. I'm asking which would work better, given that males and females would be homozygous and neutrois are heterozygous for the alleles of the sex gene: Parthogenesis or sexual reproduction. Actually, I'm leaning towards mainly sexual reproduction with the chance of parthogenesis in some instances.

    Posted November 14th, 2008 by bloodb4roses

    That seems to be the problem with a three-sex triploid species. You can't really have more of one chromosome than any of the others without taking at least one away. And I'm willing to bet it's like that for every sexually reproducing organism where the number of fertile sexes (and hence chromosomes) matches the number of chromosomes allowed per set.
    The number of kinds of sex-chromosome doesn't have to match the number of sexes nor the number of parents. If the sexes are XXX, XXY, and XYY, then 2/9 of the children will be XXX, 2/9 will be XYY, and 5/9 will be XXY. But I think for evolutionary reasons that might be unstable; if it's possible to evolve a greater probability of producing XXX and/or XYY children there will be selective pressure to do so.

    Or why don't we assume that every female delivers a default X chromosome while males have the option of producing an X or Y and hosts have the option of producing all three? That way any sex with all X's will be female, any sex with one or two Y chromosomes will be male, and any sex with a single Z chromosome will be a host?
    Well, that's exactly what I did. I just had some more detail.

    Statistically, that brings us to (I think) 15% female, 50% male, and 35% host.
    I'm not sure how you derived those numbers.
    I assumed the number of males, the number of females, and the number of hosts, would all be sort-of equal-ish; since there'd be selective pressure to have more children of whatever sex was rarer.

    Are you assuming equal numbers of X chromosomes, Y chromosomes, and Z chromosomes floating around in the gene pool?
    If so you get 1/27 of them XXX females, 7/27 of them males (XXY, XYY, and YYY), and 19/27 of them hosts (XXZ, XYZ, XZZ, YYZ, YZZ, ZZZ).
    That won't last long; the next generation won't have anyone without an X chromosome nor anyone with two or more Z chromosomes.
    So that's not what you were assuming; but I don't know what was.

    Anyway, among humans, X chromosomes outnumber Y chromosomes about 3 to 1. There are about as many women as men; almost every woman has two X chromosomes and no Y chromosomes, and almost every man has one X chromosome and one Y chromosome.

    Better yet, we can have three viable sexes, three parents, and three chromosomes per individual.
    That's also what I did.

    Not me. Too many numbers :shock:

    I might work on it sometime, and post the result.
    Here's the equations I used;
    There are four possible matings:
    XXZ-XXY-XXX, XXZ-XYY-XXX, XYZ-XXY-XXX, and XYZ-XYY-XXX.
    The first gives 1/3 hosts (2/9 XXZ and 1/9 XYZ), 4/9 females, and 2/9 males (all XXY).
    The second gives 1/3 hosts (1/9 XXZ and 2/9 XYZ), 2/9 females, and 4/9 males (all XXY).
    The third gives 1/3 hosts (2/9 XXZ and 1/9 XYZ), 2/9 females, and 4/9 males (1/3 XXY and 1/9 XYY).
    The fourth gives 1/3 hosts (1/9 XXZ and 2/9 XYZ), 1/9 females, and 5/9 males (1/3 XXY and 2/9 XYY).

    If P is the fraction of hosts who are XXZ, and Q is the fraction of males who are XXY, and if 1/3 of the children are male, 1/3 female, and 1/3 hosts, we get
    (4PQ + 2P(1-Q) + 2(1-P)Q +(1-P)(1-Q))/9 =1/3 for the female offspring, and
    (2PQ + 4P(1-Q) + 4(1-P)Q + 5(1-P)(1-Q))/9 = 1/3 for the male offspring.

    In fact, dividing the host offspring into the XXZ and XYZ types, we also get
    2PQ + P(1-Q) + 2(1-P)Q + (1-P)(1-Q) = P;
    and dividing the male offspring into the XXY and XYY types we get
    2PQ + 4P(1-Q) + 3(1-P)Q + 3(1-P)(1-Q) = Q.

    I solved that to get PP+P-1 = 0 and Q = 3P-1.

    (I wonder if I made any mistakes?)

    Posted November 14th, 2008 by chiarizio


    And which "set" would that be? What is your species' standard chromosome? For humans, the standard or default is the X chromosome. If your species is the same, each individual born from a hermaphrodite will be female. Following your first idea, you now have one sex entorely made up of females. If they hadn't speciated by then, the females would be re-absorbed into the two-sex population. Unless the hermaphrodites can also produce males by duplicating the male chromosome, it looks now like the parthenogenesis idea might be a no-win for three genders. If it can, though, one thing you could do is have an alternation between male-female sexual reproduction and hermaphrodite parthenogenesis.


    To quote MSat: Hurrrr...


    (Except for the last part) it is still a valid question.

    So far you have shown that A and B chromosomes are for male and female respectively but you haven't yet indicated how they got that way to begin with. Using humans as an example (but not as a model): the default chromosome is the X chromosome and each human has atleast one. The Y chromosome is a smaller derived form of the X chromosome but only males have one. Consequently, females are the default or species-standard sex for humans and other mammals and males are derived from them. I.e. Whatever a male has, a female has - albeit in a different form and function. Because the two chromosome pairs in your species are completely seperate from each other (neither one pair has a chromosome from the other sex), there is no way to tell which chromosome came from the other and hence which sex is the standard for the species. Unless switching from one parthenogenic parent to two sexually reproducing parents occurs in just about every sexually reproducing organism on your planet, chances are there will be a default chromosome in every species that the other sex chromosome is derived from in order for sexual reproduction to evolve. A partially parthenogenic species on Earth is only going to produce a homozygous sex because (as you said) she can only copy one of her chromosomes. She can't copy the Y or W chromosomes or then the zygote would be inviable. So what I wanted to know is which of your species' chromosomes came from which, why the two pairs are completely seperate from each other and how they got that way, and why/how the parthenogenic generation is able to produce BB males just as often as it does AA females.

    Hence the question.

    Males could produce the male chromosome exclusively and females could produce the female chromosome exclusively. Once these two chromosomes come together, they produce an AB combination which produces a hermaphrodite. The hermaphrodite then parthenogenically duplicates either A or B, meaning it sometimes produces males and sometimes produces females. Would this work?


    That's basically what I've been explaining all this time...


    Oh I see. I thought you had given up on your alternating generation idea in an earlier post and were going for an exclusively parthenogenic sex so I brought it up again and was trying to support it. Sorry for the confusion :oops:

    That seems to be the problem with a three-sex triploid species. You can't really have more of one chromosome than any of the others without taking at least one away. And I'm willing to bet it's like that for every sexually reproducing organism where the number of fertile sexes (and hence chromosomes) matches the number of chromosomes allowed per set.

    The number of kinds of sex-chromosome doesn't have to match the number of sexes nor the number of parents.


    And I never said they had to. I was simply stating the problem with using a three-sex, three-chromosome and three-chromosome set species.

    If the sexes are XXX, XXY, and XYY, then 2/9 of the children will be XXX, 2/9 will be XYY, and 5/9 will be XXY. But I think for evolutionary reasons that might be unstable; if it's possible to evolve a greater probability of producing XXX and/or XYY children there will be selective pressure to do so.


    Both XXY and XYY could be considered male because they have the Y chromosome so you would then have 7/9 be male. Those might seem like overwhelming odds on the male's side but then, in your post, you seem to have said that there will evolve greater probability for XYY - which is male, along with XXY - so apparently something like this will occur anyway.

    Or why don't we assume that every female delivers a default X chromosome while males have the option of producing an X or Y and hosts have the option of producing all three? That way any sex with all X's will be female, any sex with one or two Y chromosomes will be male, and any sex with a single Z chromosome will be a host?


    Well, that's exactly what I did. I just had some more detail.


    That was just another way of bringing up your idea. It seemed a bit too long to me so I just rephrased it. Sorry if it seemed like I was trying to steal your idea, it wasn't my intention.

    Statistically, that brings us to (I think) 15% female, 50% male, and 35% host.

    I'm not sure how you derived those numbers.


    XXX
    XXY
    XYX
    XYY
    XXZ
    XYZ

    That comes to 1/6 female, 3/6 male, and 2/6 host. Putting that into percentage, half of 100% is 50% which will be male, one third of the other half is 15% which will be female, and two thirds of that half should be 30% (not 35% - sorry, I got that part wrong).

    Are you assuming equal numbers of X chromosomes, Y chromosomes, and Z chromosomes floating around in the gene pool?
    If so you get 1/27 of them XXX females, 7/27 of them males (XXY, XYY, and YYY), and 19/27 of them hosts (XXZ, XYZ, XZZ, YYZ, YZZ, ZZZ).
    That won't last long; the next generation won't have anyone without an X chromosome nor anyone with two or more Z chromosomes.
    So that's not what you were assuming; but I don't know what was.


    I was assuming there had to be atleast one X chromosome for the offspring to be viable and, by looking at your most recent post and the calculations for the tetraploid system you devised, it seems like you agreed with me so I don't know why you didn't understand me this time. I was also assuming that as long as a sex had atleast one Y chromosome it could be male, and that some hosts would have an X and a Y on their set while others would have two X's which would cause some hosts to be more male while others would be more female, but I'm not sure whether you agree with that or not.

    Better yet, we can have three viable sexes, three parents, and three chromosomes per individual.


    That's also what I did.


    I have no idea where that came from. Guess I forgot about that first sentence...

    EDIT: Fixed the first paragraph.

    Posted November 19th, 2008 by Cerne
    Cerne
     

    Well, I was thinking that X and Y would derive from Z... Z would be their basic chromosome, the one they would always get, but the hosts would have a pair of Z chromosomes...

    But could something like this be viable?

    ZX - female
    ZY - male
    ZZ - host

    Of course, you may point out now that this time there could only be 2 parents per specimen... Those parents would be either a couple of a host and a male, a host and a female or a male and a female...

    I guess I'd just give up and forget about the tri-/tetra-ploid system and stick to this other scheme...

    Posted November 19th, 2008 by kyonides

    A partially parthenogenic species on Earth, like a Komodo dragon, is only going to produce a female because (as you said) she can only copy one of her chromosomes. She can't copy the Y or then the zygote would be inviable so she can only copy the X.


    Umm... I've said this before also, but komodo dragons are marked for being female, with the male chromosome being default, so any children produced parthenogenically are male... Komodos have WZ instead of XY like humans. W is dominant and makes an individual FEMALE. But an individual of that species has to have at least one Z chomosome. So WW is unviable. Meaning only ZZ is viable. Meaning all children produced this way for a komodo dragon are MALE.


    Moving on. Possibly both A and B where descended from some other chromosome early into the planet's history, and that was somehow out-competed by the others. I'd like to figure out what selective pressure that might be, but I like that idea so I'll keep it for now.

    Posted November 19th, 2008 by bloodb4roses

    Well, I was thinking that X and Y would derive from Z... Z would be their basic chromosome, the one they would always get, but the hosts would have a pair of Z chromosomes...

    But could something like this be viable?

    ZX - female
    ZY - male
    ZZ - host

    Of course, you may point out now that this time there could only be 2 parents per specimen... Those parents would be either a couple of a host and a male, a host and a female or a male and a female...


    ...or maybe the host could be infertile but the Z chromosome could remain a prerequisite for the viability of the offspring? Your system works quite well though, so kudos for coming up with it :thumbright:

    I guess I'd just give up and forget about the tri-/tetra-ploid system and stick to this other scheme...


    The tetraploid system works well too if you wanted to use it. See chiarizio's second-last post in this thread. It explains in greater detail how such a system could work.

    Umm... I've said this before also, but


    Fixed. Sorry, bad example. I remember you typed that Komodos used the ZW system and that they could only produce males through parthenogenesis but you didn't say anything about the W chromosome being dominant so I got confused. I meant that the default chromosome would always be produced. Guess I shouldn't have said it would be female though.

    komodo dragons are marked for being female, with the male chromosome being default, so any children produced parthenogenically are male... Komodos have WZ instead of XY like humans. W is dominant and makes an individual FEMALE. But an individual of that species has to have at least one Z chomosome. So WW is unviable. Meaning only ZZ is viable. Meaning all children produced this way for a komodo dragon are MALE.


    So parthenogenesis always produces males and sexual reproduction produces females and males? That's cool. I thought most vertebrates were XY...this would be a cool idea for a conspecies...

    Moving on. Possibly both A and B where descended from some other chromosome early into the planet's history, and that was somehow out-competed by the others. I'd like to figure out what selective pressure that might be, but I like that idea so I'll keep it for now.


    I don't think this could happen. Every new chromosome distributed by an organism has to come from some other chromosome and I don't see how a chromosome could be "selected out" or disappear from a species altogether. What might be more plausible would be if the B somehow came from the A during the evolution of sexual reproduction and this AB individual started out male.

    Here you could go into two directions:


  • Following your first idea, after a while the AB males could become sterile and only reproduce by parthenogenesis. You implied in another posts that BB males would be viable and also fertile so - even though it ignores the viability issue Earth animals have - some BB offspring could be concieved through the doubling of the B chromosome instead of the A and subsequently take over the role the AB males once had.

  • Following your second idea, the BB males could become second males and the first males could become hermaphrodites to make up for the overwhelming male-female ratio.


    In any case you obviously know what you want by now so I'll leave you to it.

    _________________

    I had a new idea: following the case with the Komodo Dragon but going in the opposite direction, would it be possible for a conspecies to produce females through parthenogenesis and males exclusively through sexual reproduction? What would I have to do in order to make this possible? Obviously I would start with the XY system but would I need to do anything special with the Y chromosome and the male's ability to produce it?

  • Posted November 21st, 2008 by Cerne
    Cerne
     

    So parthenogenesis always produces males and sexual reproduction produces females and males? That's cool. I thought most vertebrates were XY...this would be a cool idea for a conspecies...

    Most (all?) mammals have "an XY system": meaning that there is a gene for maleness which is "dominant".

    Actual "Y chromosomes", though, really only occur in a subset of Old World Monkeys (a subset which happens to contain all Great Apes as well as some, but not all, other Old World Monkeys).

    Most, if not all, social insects have a "Parthenogenesis produces males; sexual reproduction produces females" system. If an ant colony's queen dies, her virgin-female workers quit getting the fertility-suppressing pheromone from her, and start to lay fertile (though unfertilized!) eggs, from which male ants hatch. And of course if the queen lays an unfertilized egg (whether she's run out of sperm from her mating-flight, or just happens to lay an unfertilized egg), a "drone" hatches. (Among ants, males aren't really "drones" the way they are among bees; they're quite energetic about one thing -- mating. They starve to death, eventually, because they don't want to take time out to eat.)

    These insects mostly have a "monoploid = male, diploid = female" system.

    Not all eusocial animals do it that way; a naked-mole-rat queen keeps the worker-females sterile by dominating them; she's bigger and stronger.

    And IIANM ISTR some termites have (sterile, of course) male workers.

    Posted November 22nd, 2008 by eldin raigmore

    In David Gerrold's Chtorr ecology, there's a species known as "bunnymen" and "libbets". (It takes people a while to realize they're (probably) one species; "bunnymen" look nothing like "libbets".)

    A character in the book says: "If one bunnyman fucks a libbet, she has a libbet; if two bunnymen fuck a libbet, she has a bunnyman."

    To me that sounds like a triploid=male, diploid=female system; every male has three parents (a mother and two fathers), and every female has two parents (a mother and one father).

    Note, though, that there are only two sexes.

    I'm personally not convinced that would work; what if one bunnyman fucks the same libbet twice? How would her ova know not to be fertilized by his sperm? Especially if, him being triploid and his sperm being monoploid, two different sperm of his are likely to have only one-third of their genes in common?

    But, anyway, there's an additional idea.

    Posted November 23rd, 2008 by chiarizio

    Returning to the parthenogenesis issue, would it be possible for a reptile with a ZW chromosome system to temperature-sex their eggs? In lizards that use the XY chromosome system, the eggs can atleast be partially temperature-sexed - eggs kept at a certain range of temperatures will have an equal chance of being male or female but ten degrees lower and they all become female while ten degrees higher will produce all males - so I am wondering if the same thing can happen in a ZW chromosome system. If this is possible, then would incubating the eggs above the equal-sex range produce females instead of males? In the case with temperature-sexing, I am wondering if the higher amount of heat during incubation somehow ensures a heterozygous chromosome match, and if so, it would be reasonable to assume that ZW (female) offspring would be produced in a ZW chromosome system.

    Posted October 3rd, 2009 by Cerne
    Cerne
     

    Returning to the parthenogenesis issue, would it be possible for a reptile with a ZW chromosome system to temperature-sex their eggs? In lizards that use the XY chromosome system, the eggs can atleast be partially temperature-sexed - eggs kept at a certain range of temperatures will have an equal chance of being male or female but ten degrees lower and they all become female while ten degrees higher will produce all males - so I am wondering if the same thing can happen in a ZW chromosome system. If this is possible, then would incubating the eggs above the equal-sex range produce females instead of males? In the case with temperature-sexing, I am wondering if the higher amount of heat during incubation somehow ensures a heterozygous chromosome match, and if so, it would be reasonable to assume that ZW (female) offspring would be produced in a ZW chromosome system.


    Possible. It may be that in reptiles with chromosome sexing and partial heat sexing, higher heat selects for the dominant sex chromosome?

    Posted October 3rd, 2009 by bloodb4roses

    That's what I thought. OK I'll go with that until someone else tells me otherwise.

    Posted October 3rd, 2009 by Cerne
    Cerne
     

    The Male/female/host system is roughly how my Lir reproduce, glad other people have thought of the same thing and that it's possible, however my lot have a slight variation in that mating is male (like humans) mates with shan ('female', breastless, ovaries and genetalia that 'fold' and 'unfold' into yonic and phallic forms as needed), who mates with 'female' (host, with womb, breasts and third set of sex cells). The shan has to copulate with a female within a few hours of the male for the mixed cells to remain intact.
    The fact that the lir are a reasonably social species (though with very different group structure to humans) means that three sexes isn't impractical, whilst the relative uncommonality of a viably fertile male/shan/female triad is a limit on population growth which balences the species' biological immorality (more correctly 'agelessness').

    In terms of non-reproductive function and roles within the species, male and 'female' are basically the same as on earth, while the shan have a natural propensity for magic, and the way the presence of the ether has affected evolution on Avantir makes this a role in itself.

    Posted November 18th, 2009 by Rowan
    Rowan
     

    I just started a thread on my AB+A+B system, and a further complication thereof.
    here

    It's http://gtx0.com/merge/thread/777 now; conworlds.com is no more, conworlds.info is no more, and conworlds.org also is no more.

    Posted July 28th, 2011 by chiarizio


    But that's the thing. From reading kyonides' post, I can't see where he said anything about four genders or four chromosomes. Furthermore, I don't know why you put four chromosomes in each set. You can't even get more than three varients with the four-chromosome sets that you've already got. So, if you do know that tetra- means "four," what does four hav to do with any of it?

    A guess: the 50% may not necessarily mean that an extra chromosome is added. Maybe he's using a punnett square with nine boxes or something else. Just don't doubt me until you ask him or wait until he responds.



    The chromosomes would be distributed like this:
    Male - 50% Y, 25% X, 25% Z
    Female - 50% X, 25% Y, 25% Z
    Host - 50% Z, 25% X, 25% Y


    Well, I took
    "Male - 50% Y, 25% X, 25% Z" to mean "Male = XYYZ";
    "Female - 50% X, 25% Y, 25% Z" to mean "Female = XXYZ";
    and "Host - 50% Z, 25% X, 25% Y" to mean "Host = XYZZ".

    The "Punnett square" interpretation didn't occur to me. If that's what he meant I still don't quite understand it.

    The first interpretation that occurred to me was;
    Three sexes;
    Every specimen has three parents, one of each sex;
    Sex is determined by the sex-chromosomes, of which there are three kinds;
    Every specimen is tetraploid.

    As you can see that's got to be pretty complicated; if kyonides meant something else maybe it's simpler.

    Posted July 28th, 2011 by chiarizio

    The Male/female/host system is roughly how my Lir reproduce, glad other people have thought of the same thing and that it's possible, however my lot have a slight variation in that mating is male (like humans) mates with shan ('female', breastless, ovaries and genetalia that 'fold' and 'unfold' into yonic and phallic forms as needed), who mates with 'female' (host, with womb, breasts and third set of sex cells). The shan has to copulate with a female within a few hours of the male for the mixed cells to remain intact.
    The fact that the lir are a reasonably social species (though with very different group structure to humans) means that three sexes isn't impractical, whilst the relative uncommonality of a viably fertile male/shan/female triad is a limit on population growth which balances the species' biological immortality (more correctly 'agelessness').

    In terms of non-reproductive function and roles within the species, male and 'female' are basically the same as on earth, while the shan have a natural propensity for magic, and the way the presence of the ether has affected evolution on Avantir makes this a role in itself.


    More?

    Posted July 28th, 2011 by chiarizio

    ... why didn't you just create a third chromosome, let's say it's Z, instead?

    Could the following be reasonable for a conworld?

    Let's say that there's a creature with female characteristics and another one with male ones. What if both of them require to find a "host" for the new babie / cub / whatever you wanna call it?

    ….

    The chromosomes would be distributed like this:

    Male - 50% Y, 25% X, 25% Z
    Female - 50% X, 25% Y, 25% Z
    Host - 50% Z, 25% X, 25% Y

    Another option would be...

    Male - 60% Y, 10% X, 30% Z
    Female - 60% X, 10% Y, 30% Z
    Host - 60% Z, 20% X, 20% Y

    The reason why the host would be more... balanced would be that it should support either a male baby or a female one.


    This post is a (or several!) response(s) to that portion of that long-ago post of kyonides's.

    For purposes of this post (and I imagine probably its sequelae), I'm assuming:
  • there are exactly three sexes
  • each specimen has exactly three parents
  • (exactly one parent of each sex)
  • there are exactly three kinds of sex-chromosome
  • (X, and Y, and Z)
  • every specimen has the same "ploidy" as every other specimen
  • (in particular every specimen has the same total number of X-or-Y-or-Z sex-chromosomes as every other specimen)
  • a specimen's sex is determined at conception
  • by how many of which kind of sex-chromosome it has.

    (BTW this will require a "Punnett cube" instead of a Punnett square!)

    __________________________________________________

    First; what if the sexes' genotypes are as follows?
  • females are XXY or XXZ
  • males are XYY or YYZ
  • hosts are XZZ or YZZ
    and each parent contributes exactly one sex-chromosome to each offspring?
    There are then eight types of parent-sets;
  • XXY-XYY-XZZ
  • XXY-XYY-YZZ
  • XXY-YYZ-XZZ
  • XXY-YYZ-YZZ
  • XXZ-XYY-XZZ
  • XXZ-XYY-YZZ
  • XXZ-YYZ-XZZ
  • XXZ-YYZ-YZZ

    The relative numbers of zygotes of each genotype will then be;
    
    
    fem mal hos XXX YYY ZZZ XXY XXZ XYY YYZ XZZ YZZ XYZ tot
    XXY XYY XZZ 2 0 0 5 4 2 4 0 0 10 27
    XXY XYY YZZ 0 2 0 2 4 5 4 0 0 10 27
    XXY YYZ XZZ 0 0 0 4 2 2 4 4 2 9 27
    XXY YYZ YZZ 0 2 0 0 0 4 5 4 2 10 27
    XXZ XYY XZZ 2 0 0 4 5 0 0 2 4 10 27
    XXZ XYY YZZ 0 0 0 2 4 4 2 2 4 9 27
    XXZ YYZ XZZ 0 0 2 4 2 0 0 5 4 10 27
    XXZ YYZ YZZ 0 0 2 0 0 4 2 4 5 10 27
    4 4 4 21 21 21 21 21 21 78


    So out of each 216 offspring, * 90 (41.667%) will be non-viable or sterile * 4 XXX
  • 4 YYY
  • 4 ZZZ
  • 78 (86.667% of the sterile/nonviable ones, 36.111% of the whole 216) XYZ
  • 42 (19.444%) will be female * 21 XXY
  • 21 XXZ
  • 42 (19.444%) will be male * 21 XYY
  • 21 YYZ
  • 42 (19.444%) will be "hosts" * 21 XZZ
  • 21 YZZ

    __________________________________________________

    In an earlier post long ago (Posted: Wed Nov 12, 2008 2:58 pm), I already talked about what if the three sexes had the genotypes XXYZ (female), XYYZ (male), and XYZZ ("host").


    __________________________________________________


    What if they are dekaploid?

    What if:
    Females have genotype X6Y1Z3
    Males have genotype X1Y6Z3
    "Hosts" have genotype X2Y2Z6
    ?

    For one thing, to maintain dekaploidy, the various parents can't all contribute exactly the same number of chromosomes as each other.

    The evenest split would be for two of the parents to contribute three chromosomes each, and the third parent to contribute four chromosomes.

    For basically no principled reason -- just because it occurs to me first -- let's assume for a bit that the male and female each contribute three chromosomes, and the "host" contributes four chromosomes.

    Out of every 120 gametes, the Female could contribute;
  • 45 XXZ gametes
  • 20 XXX gametes
  • 18 XZZ gametes
  • 18 XYZ gametes
  • 15 XXY gametes
  • 3 YZZ gametes
  • 1 ZZZ gamete .

    Out of every 120 gametes, the Male could contribute;
  • 45 YYZ gametes
  • 20 YYY gametes
  • 18 YZZ gametes
  • 18 XYZ gametes
  • 15 XYY gametes
  • 3 XZZ gametes
  • 1 ZZZ gamete .

    Out of every 210 (not 120!) gametes, the "Host" could contribute;
  • 60 XYZZ gametes
  • 40 XZZZ gametes
  • 40 YZZZ gametes
  • 15 ZZZZ gametes
  • 15 XXZZ gametes
  • 15 YYZZ gametes
  • 12 XXYZ gametes
  • 12 XYYZ gametes
  • 1 XXYY gamete .

    My spreadsheet for this is much too large to copy here (15 columns by 444 rows).
    But the results are, out of every 3,024,000 fertilizations, about 94% are nonviable or sterile, about 0.2% are Female, about 0.2% are Male, and about 5.5% are Hosts.
    Just looking at the viable and fertile offspring, about 3.4% will be Female, about 3.4% will be Male, and about 93.1% will be Hosts.

    So this arrangement doesn't really look all that reasonable, does it?


    __________________________________________________


    All the calculating is much easier if not only do all the zygotes have the same "ploidy" as each other zygote, but also all the gametes have the same "ploidy" as each other gamete.

    In any kind of three-parent system, that would require the zygotes' "ploidy" to be exactly three times the gametes' "ploidy".

    So it might be natural to look at hexaploid and enneaploid systems.

    …. …. …. …. …. …. …. …. …. …. …. …. …. …. …. …. …. …. …. ….

    Maybe:
    Females are all either X3 Y2 Z1 or X3 Y1 Z2;
    Males are all either X2 Y3 Z1 or X1 Y3 Z2;
    and Hosts are all either X2 Y1 Z3 or X1 Y2 Z3.

    Out of every 15 gametes, an XXXYYZ Female produces:
    3 XX gametes;
    1 YY gamete;
    3 XZ gametes;
    2 YZ gametes; and
    6 XY gametes.

    Out of every 15 gametes, an XXXYZZ Female produces:
    3 XX gametes;
    1 ZZ gamete;
    3 XY gametes;
    2 YZ gametes; and
    6 XZ gametes.

    Out of every 15 gametes, an XXYYYZ Male produces:
    3 YY gametes;
    1 XX gamete;
    3 YZ gametes;
    2 XZ gametes; and
    6 XY gametes.

    Out of every 15 gametes, an XYYYZZ Male produces:
    3 YY gametes;
    1 ZZ gamete;
    3 XY gametes;
    2 XZ gametes; and
    6 YZ gametes.

    Out of every 15 gametes, an XXYZZZ Host produces:
    3 ZZ gametes;
    1 XX gamete;
    3 YZ gametes;
    2 XY gametes; and
    6 XZ gametes.

    Out of every 15 gametes, an XYYZZZ Host produces:
    3 ZZ gametes;
    1 YY gamete;
    3 XZ gametes;
    2 XY gametes; and
    6 YZ gametes.

    That would make about 43.6% of all fertilizations result in zygotes that were either nonviable or sterile, while about 18.8% would be Male, about 18.8% would be Female, and about 18.8% would be Hosts.

    There may be several ways we could improve this.
    One might be;
    let X4 Y1 Z1 individuals be Females;
    let X1 Y4 Z1 individuals be Males; and
    let X1 Y1 Z4 individuals be Hosts.

    But I don't think it's in the spirit of kyonides's post to allow XXXYYY or XXXZZZ or YYYZZZ or XXYYZZ individuals to be viable and fertile.
    Maybe I'm wrong.

    -------------------------------------------------------------------------------------

    Anyway, I'm going to turn in for the night. I may do more on this at a later time. (Or not!)

    If anyone replies, I'll probably keep posting longer than if no-one else shows any interest.

    I'll probably (but maybe not!) post at least once more even if there's no reply; after that I'll probably (but maybe not!) wait for someone's reply.

  • Posted August 30th, 2016 by chiarizio

    Ok so, as a possible sex determining system in a species that has 3 (or more) sexes, all three sexes contribute genetic info and the species is triploid:

    - There are three types of sex chromosomes X, Y and Z.
    - All individuals MUST have at least 1 X chromosome or the fetus is not viable.
    - Otherwise all sex chromosome combos are allowed
    - Assuming normal maturation, XXX always codes for one sex, XXY a second sex and XXZ a third. XYZ individuals can be either of the sexes associated with the Y or Z chromosomes, but that is environmentally controlled somehow, probably so they were more likely to become the rarer of the Y or Z sexes. XXX would probably be female if I use this set up.

    I'm not sure if there would be any specific reason XXX couldn't be one of the "male" sexes, but there might be some reason.

    Posted August 30th, 2016 by bloodb4roses

    Ok so, as a possible sex determining system in a species that has 3 (or more) sexes, all three sexes contribute
    ….
    I'm not sure if there would be any specific reason XXX couldn't be one of the "male" sexes, but there might be some reason.


    You ninja'ed my last edit; but I'm glad you replied!

    So far, I've been assuming that every individual requires at least one X and at least one Y and at least one Z.

    And, if more than half of an individual's sex-chromosomes were X, it would be "female" (or whatever we want to call that sex); if more than half were Y, it would be "male" (or whatever we want to call that sex); and if more than half were Z, it would be a "host" (or whatever we want to call that sex).

    Normally I've also been assuming that if it had more X chromosomes than Y chromosomes and also more X chromosomes than Z chromosomes, it would be "female"; if it had more Y chromosomes than X chromosomes and more Ys than Zs it would be "male"; and if it had more Zs than Xs and more Zs than Ys it would be a "host".

    I have been assuming that, if it weren't a female nor a male nor a "host", it must be either non-viable or sterile.

    So if it has as many Xs as Ys, or as many Xs as Zs, or as many Ys as Zs, and those two types of sex-chromosomes are "tied for most" (maybe a two-way tie, or maybe a three-way tie), I've been saying it's nonviable or, at best, sterile.

    Your idea sounds good to me; at least it's worth looking into.

    For one thing, maybe sex is controlled at conception only if one type of sex-chromosome does, in fact, outnumber [color=#606060]botheach of the other types. Otherwise, the environment might choose either of two sexes if there's a two-way tie, or any of three if there's a three-way tie.

    Mostly, individuals with ambiguous sex will be unable to mate, or have a lot of trouble anyway, either with mating or with something else having to do with reproducing. But if the environment weighs in, in cases where the chromosomes don't finish determining the sex, there would still be more ambiguity among individuals so concerned than among those whose sex was completely determined by their chromosomes, but there would be much less ambiguity than if there was no way to finish determining the sex of an individual whose genotype didn't completely determine it. Only if the environment were also ambiguous somehow, would the individual's ultimate sex remain ambiguous.

    IRL, though, among most* species with "sex chromosomes", one type of chromosome (X or Z) is absolutely essential for the continued life of the zygote, and for its chances to be born and mature. Either that's the only type of sex-chromosome (X), and individuals with two of them (XX) are one sex (e.g. female) while individuals with only one of them are the other sex (e.g. male); or else there's a second type of sex-chromosome (e.g. Y or W), and an individual that has one of this second type is one sex (e.g. XY males or ZW females), while an individual without a sex-chromosome of this second type are the other sex (e.g. XX females or ZZ males).

    *([edit]There has been an example in nature of a female boa constrictor with karyotype WW. Apparently there have been many more laboratory-created examples in other ZW/ZZ species.[/edit])

    _____________________________________________________________

    If there's a sex which are all and only XXX, and everyone needs an XXX parent, then everyone will have at least one X chromosome.
    If everyone has to have three parents, no two of the same sex, then the only way an XXX individual can be conceived, is if each of its parents carries at least one X.
    So there's a connection between one sex being all and only XXX, and a requirement that a zygote must have an X chromosome to be viable.

    If an individual needs at least one XXX parent,
    and at least one parent who is either XXY or XYY or XYZ,
    and at least one parent who is either XXZ or XYZ or XZZ,
    then there's going to be a possibility that some zygote will be XYZ.

    In fact, if a mating trio's first partner is an XXX,
    and its second partner is either an XXY or an XYZ,
    and its third partner is either an XXZ or an XYZ,
    then there's a good chance that some zygotes will be XYY or XZZ (or XYZ).

    XXX-XXY-XXZ will have 4/9 XXX, 2/9 XXY, 2/9 XXZ, and 1/9 XYZ.
    XXX-XXY-XYZ will have 2/9 XXX, ⅓ XXY, 2/9 XXZ, 1/9 XYY, and 1/9 XYZ.
    XXX-XYZ-XXZ will have 2/9 XXX, 2/9 XXY, ⅓ XXZ, 1/9 XYZ, and 1/9 XZZ.
    XXX-XYZ-XYZ will have 1/9 XXX, 2/9 XXY, 2/9 XXZ, 1/9 XYY, 2/9 XYZ, and 1/9 XZZ.

    (For now I'll put off calculating the Punnett squares for the five other combinations; those with either an XYY parent or an XZZ parent or both.)

    I am guessing that you intend the XYY individuals to be the same sex as the XXY individuals, and intend the XZZ individuals to be the same sex as the XXZ individuals? You've said they are viable; am I right to guess they aren't sterile?

    …. …. …. …. …. …. …. …. …. …. …. …. …. …. …. …. …. …. …. ….

    IRL in some species the individuals with all one kind of sex-chromosome are the males, and those with two different kinds are the females. So, I doubt there's a reason the XXX need to be the females, in your proposed example. (Of course, "the author just decided to make it that way" is a perfectly valid reason; I meant, I doubt there's any other reason!)

    Posted August 30th, 2016 by chiarizio

    Ah yes, XYY would be the same sex as XXY, and XZZ same as XXZ. I suppose an alternate system with more possible sexes could make these separate, but "related" sexes.

    Posted August 31st, 2016 by bloodb4roses

    Somewhat in line with my own last few posts, and also with bb4r's last few posts, are the following two proposed systems.

    Let there be three sexes, which will call "female" and "male" and "host" without necessarily meaning anything by those names, in particular without connect "female" to RL female nor "male" to RL male.
    Let there be three sex-chromosomes, which will call X and Y and Z, without necessarily connecting them to RL X or Y or Z chromosomes.

    Assume every specimen needs at least one X chromosome to develop, come to term, hatch or be born, survive, and grow to adulthood.
    Assume, also, every specimen needs either at least one Y chromosome or at least one Z chromosome, to develop, come to term, hatch or be born, survive, and grow to adulthood.

    First proposal: triploidy.
    Assume any specimen with two Xs is Female.
    Assume any specimen with two Ys is Male.
    Assume any specimen with two Zs is a Host.
    Assume any specimen with one X and one Y and one Z can grow to be any of the three sexes, depending on environmental factors (such as which sex of its own age it meets fewest of before pubescence).

    Then female genotypes can be XXY or XXZ or XYZ;
    male genotypes can be XYY or XYZ;
    and hosts' genotypes can be XZZ or XYZ.
    (XXX, YYY, ZZZ, YYZ, and YZZ, are all non-viable.)

    Females' gametes can be X or Y or Z, depending on the female's genotype.
    Males' gametes can be X or Y or Z, depending on the male's genotype.
    Hosts' gametes can be X or Y or Z, depending on the host's genotype.

    If we temporarily omit the XYZ genotype, there are just two types of matings:
  • XXY female - XYY male - XZZ host, or
  • XXZ female - XYY male - XZZ host.

    In the first instance,
    the female's gametes will be ⅔ X and ⅓ Y;
    the male's gametes will be ⅓ X and ⅔ Y;
    and the host's gametes will be ⅓ X and ⅔ Z.
    The zygotes will be:
    10/27 XYZ, environmentally determined,
    5/27 XXY (female),
    4/27 XXZ (female),
    2/27 XYY (male),
    4/27 YZZ (non-viable), and
    2/27 XXX (non-viable).

    In the second instance,
    the female's gametes will be ⅔ X and ⅓ Z;
    the male's gametes will be ⅓ X and ⅔ Y;
    and the host's gametes will be ⅓ X and ⅔ Z.
    The zygotes will be:
    10/27 XYZ, environmentally determined,
    5/27 XXZ (female),
    4/27 XXY (female),
    2/27 XZZ (host),
    4/27 YYZ (non-viable), and
    2/27 XXX (non-viable).

    But there's a possibility any one, or any combination of two, or all three, of the three parents might be XYZ. For instance:* XXY female -- XYY male -- XYZ host
  • XXZ female -- XYY male -- XYZ host
  • XXY female -- XYZ male -- XZZ host
  • XXZ female -- XYZ male -- XZZ host
  • XYZ female -- XYY male -- XZZ host

    For example 1,
    the female's gametes will be ⅔ X and ⅓ Y;
    the male's gametes will be ⅓ X and ⅔ Y;
    the host's gametes will be ⅓ X and ⅓ Y and ⅓ Z.
    Zygotes will be
    7/27 XXY female,
    2/27 XXZ female,
    7/27 XYY male,
    5/27 XYZ, environmentally determined,
    2/27 XXX non-viable,
    2/27 YYY non-viable,
    2/27 YYZ non-viable.

    For example 2,
    the female's gametes will be ⅔ X and ⅓ Z;
    the male's gametes will be ⅓ X and ⅔ Y;
    the host's gametes will be ⅓ X and ⅓ Y and ⅓ Z.
    Zygotes will be
    7/27 XYZ environmentally determined,
    6/27 XXY female,
    3/27 XXZ female,
    4/27 XYY male,
    1/27 XZZ host,
    2/27 XXX non-viable,
    2/27 YYZ non-viable,
    2/27 YZZ non-viable.

    For example 3,
    the female's gametes will be ⅔ X and ⅓ Y;
    the male's gametes will be ⅓ X and ⅓ Y and ⅓ Z;
    the host's gametes will be ⅓ X and ⅔ Z.
    Zygotes will be
    7/27 XYZ environmentally determined
    6/27 XXZ female
    3/27 XXY female
    4/27 XZZ host
    1/27 XYY male
    2/27 XXX non-viable
    2/27 YYZ non-viable
    2/27 YZZ non-viable

    For example 4,
    the female's gametes will be ⅔ X and ⅓ Z;
    the male's gametes will be ⅓ X and ⅓ Y and ⅓ Z;
    the host's gametes will be ⅓ X and ⅔ Z.
    Zygotes will be
    7 XXZ female
    2 XXY female
    7 XZZ host
    5 XYZ environmentally determined
    2 YZZ non-viable
    2 XXX non-viable
    2 ZZZ non-viable

    For example 5,
    the female's gametes will be ⅓ X, ⅓ Y, and ⅓ Z;
    the male's gametes will be ⅓ X and ⅔ Y;
    the host's gametes will be ⅓ X and ⅔ Z.
    Zygotes will be
    8 XYZ environmentally determined
    3 XXY female
    3 XXZ female
    2 XYY male
    2 XZZ host
    4 YZZ non-viable
    4 YYZ non-viable
    1 XXX non-viable

    And so on.

    The next ones to consider are: * female is XXY -- male is XYZ -- host is XYZ
  • female is XXZ -- male is XYZ -- host is XYZ
  • female is XYZ -- male is XYY -- host is XYZ
  • female is XYZ -- male is XYZ -- host is XZZ
    Perhaps later I'll work these out. It's getting late and I still need to go to the grocery store for the four-day weekend.

    _____________________________________________

    At some point I was going to consider hexaploidy.
    Female genotypes: X5 Y1, X5 Z1, X4 Y2, X4 Y1 Z1, X4 Z2, X3 Y2 Z1, X3 Y1 Z2;
    Male genotypes: X1 Y5, X2 Y4, X1 Y4 Z1, X2 Y3 Z1 , X1 Y3 Z2;
    Host genotypes: X1 Z5, X2 Z4, X1 Y1 Z4, X2 Y1 Z3, X1 Y2 Z3;
    May either be female or male, depending on environment: X3 Y3;
    May either be female or host, depending on environment: X3 Z3;
    May be female or male or host, depending on environment: X2 Y2 Z2;
    non-viable: X6, Y6, Z6, Y5 Z1, Y4 Z2, Y3 Z3, Y2 Z4, Y1 Z5.

  • Posted September 2nd, 2016 by chiarizio

    So, more or less, the XYZ individuals are more flexible, in that they will "fill out" the population to balance the sexes, but on average will have slightly fewer offspring, all else being equal, because the chance of nonviable zygotes being more likely to be produced.

    But depending on how they develop before adolescence, it might be impossible to tell what someone will develop into until puberty anyway. Otherwise,there would be members of the species that are distinctly one sex or another, and then some children who were obviously "androgynous" (tho that word isn't quite right considering the origin.)

    Posted September 2nd, 2016 by bloodb4roses

    Excellent summary. Wish I'd thought of it first!

    My idea is that some youngsters will have their sex determined at conception, and these will give off at least some pheromones of the appropriate sex even before pubescence.

    For those whose adult sex will be determined (partially?) environmentally, their bodies will "steer" them toward the sex that is rarest among their fellow adolescents. Or, if they can be one of two sexes, but not of all three, towards whichever of those two sexes is rarest among their age-mates.

    (Maybe it'll help if all young'uns also give off a juvenile pheromone that begins to wane as they reach pubescence, and disappears as they reach maturity. The XYZ kids will do this, too; they just won't give off the pheromones unique to any one sex, until they actually pubesce, and even then not as strongly as the others until they actually mature.)


    _____________________________________________________________




    At some point I was going to consider hexaploidy.

    I mentioned enneaploidy and dodekaploidy too. I never intended to go into detail about dodekaploidy; but enneaploidy may be worth a close look.
    Among the phenomena that occur with enneaploidy but not with hexaploidy:
  • X4Y3Z2 and X4Y2Z3 karyotypes will be "female" in spite of having fewer than half of the sex-chromosomes be Xs.
  • Similarly, X3Y4Z2 and X2Y4Z3 karyotypes will be "male" in spite of having fewer than half of the sex-chromosomes be Ys; and X3Y2Z4 and X2Y3Z4 will be "host" in spite of fewer than half the sex-chromosomes being Zs.
  • X4Y4Z1 youngsters may mature into either Female or Male adults, depending on environment, but not into Host adults.
  • And X4Y1Z4 youngsters may mature into either Female or Host adults, depending on environment, but not into Male adults; while X1Y4Z4 youngsters may mature into either Male or Host adults, depending on environment, but not into Female adults.
  • But X3Y3Z3 youngsters may mature into any of the three sexes as adults, depending on environment.

    _____________________________________________________________



    One interesting possible problem with the "mature into the rarest sex" idea, is that, in for instance the hexaploid case, suppose females outnumber males outnumber hosts in the ratio 4:3:2. Then the X3Y3 adolescents will all become males, while the X3Z3 and X2Y2Z2 adolescents will all become hosts. It's possible that, rather than simply correcting the imbalance, this will overcorrect, to make an imbalance going the other way! But perhaps it will always be a lesser imbalance; in which case it will eventually settle back down into an equilibrium. OTOH if it can ever lead to a greater imbalance, that could be a real problem.

    One of us will have to investigate that; right?

    Later for me, though; my daughter is with me and we need to go shopping. (And I need to concentrate on her this weekend and holiday!)

  • Posted September 3rd, 2016 by chiarizio

    Any new interest in this topic?
    Anything to add?

    Posted May 4th, 2018 by chiarizio

    Is @bb4r, or anyone else, still interested in this?

    Posted August 15th, 2018 by chiarizio

    Is @bb4r, or anyone else, still interested in this?


    I am still interested in this subject I just don't have anything new to add.

    Posted August 15th, 2018 by bloodb4roses

    Is @bb4r, or anyone else, still interested in this?

    I am still interested in this subject I just don't have anything new to add.


    How ‘bout now? :mrgreen:

    Posted December 12th, 2018 by chiarizio

    Is @bb4r, or anyone else, still interested in this?

    I am still interested in this subject I just don't have anything new to add.


    How ‘bout now? :mrgreen:


    Actually yes. I just had a thought about temperature determined sex systems.

    AFAIK, most temp based systems on Earth don't split nicely into high temp = one sex, and low temp = the other. Instead, one sex is a middle temp incubation and the other sex occurs when eggs are both too hot or too cold.

    In the case of muti-sex species, they could also have incubation at the "preferred" temp result in one sex and have "rings" of temps for other sexes dependent on how many of that sex is needed. Sexes that can easily be much rarer and the population still have enough to reproduce and be healthy would be the farthest from the preferred temp, and the sex that restricts the population the most would need to be the closest to the preferred incubation temp, so there could be as many as possible.

    Alternately, the preferred incubation temp could result in one sex, but lower temps result in a second, and higher ones in the third. (Or such if there's more than three sexes.) This could at least keep the sex ratios slightly more even in times of stability, but might lead to bottlenecks or extinction during times of climate change or when moving from one environment to another.

    There could even be a combination between genes and temperature for the species, so that say, with genes AA and incubation at X temperature range, you get one sex, but AB at the same range gets you a different sex, or AB individuals might have a broader or narrower range to be that one sex, etc. This could be its own subset of discussion. Depending on how it worked, it could even "smooth out" some of the issues with temp based sex selection on its own.

    Posted December 12th, 2018 by bloodb4roses

    I like it! I’ll try to think about it and come up with variations.

    Posted December 12th, 2018 by chiarizio

    How about:
    If they’re incubated btwn 25 and 40 degrees C they’re sex A;
    If they’re incubated btwn 5 degrees and 25 degrees C, or between 40 degrees and 60 degrees C, they’re sex B;
    And if they’re incubated between 0 degrees and 5 degrees C, or between 60 degrees and 100 degrees C, they’re sex C.

    If they’re incubated at temps cooler than 0 degrees C or warmer than 100 degrees C, they probably will not hatch.

    —————

    Fahrenheit for my fellow USAmericans.

    If they’re incubated btwn 77 and 104 degrees F they become sex A.
    If they’re incubated between 41 and 77 degrees F, or between 104 degrees and 140 degrees F, they become sex B.
    If they’re incubated between 32 degrees and 41 degrees F, or between 140 degrees and 212 degrees F, they become sex C.

    If they’re incubated cooler than 32 degrees F or warmer than 212 degrees F, they probably don’t hatch.

    —————

    One or another or two or all three of the parents, or the quasiadult siblings, might need to stay and tend the eggs of sex A in very cool or very warm places or times, or of sex C in more moderate times.

    For instance, suppose temps stayed btwn about 4C to 26C (37F to 79F). Someone would have to cool some of the eggs to get sex C hatchlings, and/or warm some of the eggs to get sex A hatchlings.
    Or, suppose temps stayed btwn 37.5C and 61C (98.6F and 142F). Someone would have to cool some of the eggs to get sex A hatchlings, and/or warm some of the eggs to get sex C hatchlings.

    If temps stayed between -1C and 6C (30F and 43F), the eggs would need to be warmed a little to hatch at all, warmed more to hatch as sex B instead of sex C, and warmed a lot — at least 14 degrees C (25 degrees F) to hatch as sex A.

    If temps stayed between 24C and 41C (75F and 106F), nearly all hatchlings would be sex A unless the eggs were warmed or cooled. A little cooling would cause them to hatch as sex B; so would a little warming. If they were cooled more than about 19 degrees C (36 degrees F), or warmed more than about 19 degrees C (36 degrees F), they might hatch sex C.

    If temps stay in the range 59C to 101C (134F to 214F), they might need to be cooled a little just to be sure they actually hatch instead of stifling. OTOH a little cooling might be all it would take to get some sex B hatchlings (otherwise they’d be sex C). It would take 19 degrees C or 36 degrees F of cooling to get any sex A hatchlings.

    —————

    I don’t know how well that would work out for them.

    We might need to add in some of the other ideas in your post, to make the species stay viable.

    Posted December 14th, 2018 by chiarizio

    I'd think that the temperature range would be much smaller than this. IIRC most creatures that use this way of sex determination only need the tamp to drop or raise a little bit (a few degrees Celsius at most) during a certain crucial period for an egg to develop one way or the other.

    So maybe the entire incubation tries to stay within 15 degrees Celsius, at least a majority of the time. And the temperature during a three day period around the 4th week (for example) of incubation is actually what decides the sex of a given member of this species. Now the eggs could survive for short periods at slightly higher or lower temps, but in a short time, the developing fetus would be too cold or too hot and die.

    So of course, you'd want to keep most of the eggs at the middle of the range, but some will still be cooler or warmer. This middle range would be best served being the most female-like sex, and if more members of a certain sex are needed. some eggs can be incubated at higher or lower temps.

    Posted December 16th, 2018 by bloodb4roses

    1. That makes sense.

    2. Thanks for clarifying the Real Life version for me!

    3. So, we might want
    sex A to be the females,
    sex B to be the eggfathers, and
    sex C to be the spermfathers? That is,
    the females in the central temps,
    the egg-fathers in the temps a little warmer or cooler than that, and
    the spermfathers in the outlying temps?

    Females if the egg stays between 35 and 40 degrees C the whole incubation;
    eggfather younglings if the temp goes between 32.5 and 35, or between 40 and 42.5 degrees C, for 3 days during the 4th week; and
    spermfathers-to-be if the temp cools to between 30 and 32.5, or warms to between 42.5 and 45, degrees C, for 3 days during the 4th week?

    I’m aware those precise temps would strike a human, or at least your average USAnian office worker, as a bit warm! 30C is 86F and 45C is 113F! But your conpeople needn’t be human, right?

    Maybe the middle range is 20C to 23C,
    with the second sex being 18C-20C or 23C-25C for 3 days in the fourth week, and the third sex being 16C-18C or 25C-27C for 3 days in the 4th week.
    16C is about 60.8F, 18C is about 64.4F, 20C is about 68F, 23C is about 73.4F, 25C is about 77F, and 27C is about 80.6F.
    More comfortable?

    Posted December 17th, 2018 by chiarizio

    Something like what you said, chiarizio. I don't know what specific temps would work but I suppose it depends on the biochemistry of the species and such. Though for mine, it would be close to human-friendly temps, yes.

    Also, with partial genetic sex typing, you could easily turn this into a 4 sex system (have sex chromosomes that only affect things in a certain temp range), 5 sex system (sex chromosomes have different effects in two temp ranges, but none in the third) or 6 sex system (sex chromosomes and temp each have specific effects) very easily.

    Posted December 17th, 2018 by bloodb4roses

    ...
    Also, with partial genetic sex typing, you could easily turn this into a 4 sex system (have sex chromosomes that only affect things in a certain temp range), 5 sex system (sex chromosomes have different effects in two temp ranges, but none in the third) or 6 sex system (sex chromosomes and temp each have specific effects) very easily.

    That’s right, and interesting! I’m sort of “thinking about thinking” about some such systems; but no completed thoughts yet.

    Posted December 18th, 2018 by chiarizio

    If the eggs need to be incubated near a temperature close to the average healthy RealLife human body temperature, maybe the ranges should be:
    A. 36.5-37.5 degrees C (97.7-99.5 degrees F)
    B. 36-36.5 or 37.5-38 degrees C (96.8-97.7 or 99.5-100.4 degrees F)
    C. 35.6-36.5 or 38-38.4 degrees C (96.1-96.8 or 100.4-101.1 degrees F)

    I don’t know about your mom; but if I ran a temp of 100.4*F my mom would keep me home from school but not take me to see the doctor.
    However if I ran a temp of 101.1*F she’d have taken me to the pediatrician’s clinic.
    I’m pretty sure if I’d run a temp of 99.5*F she’d have given me some over-the-counter meds and an extra sweater and a note to the teacher and sent me to school.

    I don’t know what she’d think of low temps, like 97.7*F or 96.8*F or 96.1*F.
    to the best of my knowledge, AFAICR, I never had a lower-than-normal temp under her care.

    Mayoclinic.org wouldn’t call 96.1*F “hypothermia”. They say “hypothermia” is 95*F or cooler. OTOH they say to call 911 if anyone’s temp gets lower than 95*F.
    I’d imagine they’d recommend warming someone up from 96.1 or 96.8 or 97.7 degrees F; but not necessarily calling 911.

    Sharecare.com says temps between about 97.5 and 99 degrees F are normal, but if your temp is around 96 or 97, you’re probably not sick unless you have other symptoms.

    MedlinePlus.gov says 99 or 99.5 degrees F might be normal for adults depending on time of day. Selfcare.info says not to worry about temps up to 100.4*F. ClevelandClinic.org says fevers cooler than 102*F can be treated at home, but warmer than that you should consult a physician and maybe stay in an infirmary or clinic or hospital.

    So the 96.1-99.5*F ranges are probably not sick, and the 99.5-100.4*F range is probably “a beneficial fever”, while the 100.4-101.1*F range is a treatable-at-home fever.

    96.1-101.1*F is awfully hot for room temperature, but maybe eggs need to be incubated closer to adult body temperature than to room temperature. So whatever adult —— parent or older (half?-)sibling or parent’s (half-?)sibling or grandparent, of whichever sex —— is brooding the eggs, may need to bare a brood-patch and sit on them.

    If there’s any danger the eggs might dry out, the brooder might also secrete or sweat colostrum to keep the eggs hydrated; the colostrum might even start to contain nutrients when the eggs have nearly used up their yolks.

    OTOH if the gestation is all internal, or the critical sex-determining time comes when the young is in the mother’s marsupium, the temperature at which the embryo or fetus is kept would be very close to the mother’s body-temperature, and would depend on her health and her environment.

    Would any given litter probably all be the same sex, or at least differ only because they have different chromosomes, not different brooding temperatures?

    ———

    I can actually see the interaction between sex-chromosome karyotypes and incubation-temperatures, producing up to nine sexes: for instance, if there were three viable karyotypes, and a three-ringed set of temperature ranges. But if I recall correctly, you wanted from three to seven “sexes”?

    I don’t see how you intend three parents to make genetic contributions to the offspring—— if that’s what you intend. And, how many kinds of sex-chromosomes will there be? And how many parents will contribute them? And which karyotypes will be viable?

    Posted January 2nd by chiarizio


    Oh, right- the best way to incorporate more sexes would be to have an organism made up of several two sexed species (like a lichen, but an animal), where each species has to procreate- that results in as many mandatory sexes as you need (just make a multidimensional table of the possibilities).


    Among the four (so far) sapient “races” in my multiracial fantasy world, my most recently conceived are the MerCentaurs; something like a three way chimerical mix of merfolk, centaurs, and hippocampi.
    They might have eight sexes, if the human part could be male or female, and the horse part could be male or female, and the fish part could be male or female, all independently.

    I could complicate things by allowing the fish part to do something RL fish actually do. For instance, young adults could be male and older adults could be female or vice-versa. Or the sex of the fish part could depend on incubation temperature. Or it could depend on which adult sex it encountered the most of as an egg or larva or embryo or fetus (i e if it runs into more male-fish-part adults than female-fish-part adults it grows up female, but if it meets more female than male adult fish parts it grows up male).

    ————————

    If I give these people crab-claws, like the Classical Greek ichthyocentaurs sometimes had, .... but I’m not planning to do that. These are my own creations.

    Posted January 8th by chiarizio
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