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Are there any animal species that have two sexes and a kind of different internal diversification in two genders or more? I don't mean something like different-task-based diversity, but something biological? For example let's imagine a species with:

  • 2 sexes (male and female)
  • 2 gender (A and B)

and individuals can match iff they are not only of different sex but also of different gender. So you can only have Ma-Fb, Mb-Fa.

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    $\begingroup$ What sort of other classification are you thinking of? There are lots of different classifications, e.g. both male and female humans can have any of the four blood groups. Another example could be dogs (or a lot of other animal species) where another classification is race - each race has male and female dogs. $\endgroup$ – Armatus May 11 '14 at 13:18
  • $\begingroup$ I would exclude those features because they don't determine directly the matching process (dogs don't match iff they are of different races, human beings don't if they are of different blood group). I've in mind some kind of upper-level biological feature, like sex is (different apparatus), that can influence sexual-selection. $\endgroup$ – alessandro May 11 '14 at 19:19
  • $\begingroup$ You might find some things of interest with the search term 'alternative reproductive tactics'. $\endgroup$ – Oreotrephes May 12 '14 at 19:32
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    $\begingroup$ Your definition isn't very good. For instance, a monolingual German speaker and a monolingual French speaker are extremely unlikely to "mate" in a conventional reality (in fact, there is even evidence somewhat supporting this). Obviously it's preposterous to call them "different genders", however. $\endgroup$ – Superbest May 12 '14 at 19:38
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    $\begingroup$ @Remi.b That depends on you definition of gender. A fairly common definition is to see gender as a social construct (gender identity), which means that different sexes doesn't necessarily imply different genders. $\endgroup$ – fileunderwater Dec 22 '16 at 12:16
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Many organisms have multiple sexes. For instance, here is one which apparently has 7 (and each sex, or "mating type" can only mate with the others). The "gotcha" is that, mostly, they're unicellular organisms where mating in itself is weird to begin with. I haven't ever heard of a metazoan which truly has more than one sex (there may be variation within the males or females, but I think the sperms or eggs are always interchangeable).

Gender, I think, is more of a social term relevant to human behavior. Especially nowadays, so much of the literature and understanding of what is referred to as "gender" is closely linked to things such as gender identity, sexuality, gender roles and personality that is difficult to see how you could meaningfully speak about the "gender" of (non-human) animals.

It's analogous to the idea of "animal language" - certainly some animals may be said to behave in stereotypical ways which influence their mating behavior. Does that mean that what is written about human gender applies? I suspect precious little of it would. I would be quite skeptical of someone discussing gender (in the modern sense) for even uncivilized humans, let alone non-human animals.

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I'm not sure what you mean by "gender" in the context of non-human organisms. Gender is usually defined as the intersection between biologically determined sex, and the surrounding culture.

Maybe you could argue that in social insects like, say, ants, the fertile queen and the infertile female workers diverge so much in behavior and gene expression that they aren't the same "sex", or that they could be considered different "genders", but I think that is really stretching the usual definitions of those terms.

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There are hermaphrodites and gender changing (M->F, F->M) fish. Also occasionally, there are also individuals who are neither male nor female, which may or may not count here.

However, I haven't seen 3+ separate genders except for fungi, which might occasionally be multicellular, but probably not what you are thinking of. Fungal genders are so many because they define combinations where mating is compatible. This news story has a decent summary of why as far as gametes goes, larger animals are known to have only 2 gametic genders, while fungi can have thousands. You might say that bacteria have gender when they want it (when they have a pili-containing plasmid) and otherwise they have none - any individual may transfer DNA to another under the right conditions (like death).

I know this isn't what you are asking about, but this is the closest I can find. Digging around, biologist Joan Roughgarden has written a book "Evolution's Rainbow" about cases where there may be more than one social role in a given species for biologically male or females - dominance, display, homosexuality and behaviors like this. Social gender roles has been a way of talking about the biological nature of human social roles since the 1970s - see also Sarah Hrdy.

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    $\begingroup$ You're right when you say that social gender is the closest notion to what I might be looking for. A question: can a social gender of a certain individual change over time? If yes, I would exclude it from my research because I'm looking of something can't change naturally over time, as sex does. $\endgroup$ – alessandro May 11 '14 at 19:23
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    $\begingroup$ I really believe the social gender can change over time - I think if you look around you will find lots of human examples. Its harder to decide for animals but I'd be surprised there were no supporting cases to be found. Animals including humans have this wonderful but slippery quality when it comes to their personality/identity - they can learn and change. Large changes in social environment can usually change us all a lot. For people you should look at the Big Five personality tests - might give you some ideas? $\endgroup$ – shigeta May 12 '14 at 3:09
  • $\begingroup$ Are there any computational model of sexual reproduction? $\endgroup$ – alessandro May 20 '14 at 8:15
  • $\begingroup$ too many to count. from cell division to population models. ask a question, but maybe think about what sort of model you'd like. pop = pop * 3.5 - deaths; is a population model. $\endgroup$ – shigeta May 20 '14 at 12:43
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Tetrahymena thermophila is an organism with 7 different "fuzzy" genders, not only male and female. Its seven sexes are rather prosaically named I, II, III, IV, V, VI and VII. An individual of a given sex can mate with individuals of any except its own, so there are 21 possible orientations. Here is the link: Zoologger: The hairy beast with seven fuzzy sexes

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The closest thing you will find to what you're looking for, I think, are animals with multiple different mating strategies where one sex (usually the male) can have multiple distinct phenotypes. Some examples include:

Patas monkeys, where some males are large and have harems of females while others are dubbed "sneak maters" and instead of having their own harem they sneak in and mate with females in another male's harem

Scarab beetles, where males either have a horn or lack one. Horned males defend their females at their tunnel entrances while hornless males sneak into tunnels to mate with females

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  • $\begingroup$ (I also remember reading about this one species of waterfowl that had three distinct male phenotypes, but I can't remember the name off the top of my head, so if anyone else knows what I'm thinking of go ahead and comment) $\endgroup$ – C_Z_ May 8 '15 at 16:21
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Yes, it is called Alternative Mating Strategies and is well known. As an example High-backed pygmy swordtail (a fish) are known for having two types of males, one that is large and aggressive and another that is small and looks like a female to avoid aggression from other males.

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The males of some Lake Tanganika cichlid species such as Lamprologus callipterus exhibit extreme dimorphism of behaviour and size (see e.g. https://www.jstor.org/stable/40407772). These represent alternative reproductive strategies for mating with the same female population though; the big aggressive 'nest males' attempt to guard a 'harem', while the small 'dwarf males' attempt to sneak in, exploiting the fact that they look similar to females and can sometimes deceive the nest males.

I'm not sure this is completely answers your question though. The assortative "Ma-Fb, Mb-Fa" example you give almost certainly does not occur (at least for long) since that would result in two reproductively isolated populations which would speciate rapidly.

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The white-throated sparrow has two sexes (male or female), but also has an addition "gender" (tan or stripe).

So male will only mate with female. AND Tan will only mate with Stripe

This behavior is probably due to a massive chromosome inversion of 1100 genes on chromosome 2. It is starting to cause the birds to act as if it were a second sex chromosome.

http://www.nature.com/news/the-sparrow-with-four-sexes-1.21018

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