Most (maybe all?) species that reproduce sexually have either genders (anisogamy) or mating types (isogamy). There exist today many different type of sexual determination system. There is a whole complicated continuum from species where the gender is exclusively determined genetically (genetic determination system, GSD) to those where the gender is determined by the environment (environment determination system, ESD).

Knowing that genders (and mating types) evolved several independently, what seem to be the ancestral states of sex determination system? Where the first sexually reproducing lineages GSD or ESD? Does it differ between lineages?

  • $\begingroup$ I saw a talk a couple of years back, many esd systems are strongly g*e. So there is a threshold of the environmental factor where all become one sex or the other. Then at intermediate environmental values you can develop males and females $\endgroup$ – rg255 Oct 18 '14 at 7:42
  • $\begingroup$ Yes, as argued in Evolution of Sex Determination all liability factor (factor that define the sex relative to a threshold) follows a norm of reaction and therefore the concept of GSD makes sense only by defining the range of environmental condition where which the sex is only defined by the genes. But I think my question is still of interest even to the light of a more accurate definition of GSD and ESD. $\endgroup$ – Remi.b Oct 18 '14 at 15:27
  • $\begingroup$ Agreed. On another note,do you have that book? I nearly bought it this week -what do you think of it (assuming you do have it?) $\endgroup$ – rg255 Oct 18 '14 at 15:38
  • $\begingroup$ No, I don't have it. I very often want to buy it but I stop right before doing so when I see its price! I read part of this book during my master degree, just before it got published for a class I attended at the University of Lausanne with Nicolas Perrin (one of the two authors) and I really appreciate it. It was for me a totally new subject and the book made a good job to introduce me into it. I also thought that the book makes a good job of providing both a good theoretical understanding and a rather impressive list of study cases separately into different paragraphs. $\endgroup$ – Remi.b Oct 18 '14 at 15:48
  • $\begingroup$ I bought the book, they printed the pages upside down... $\endgroup$ – rg255 Dec 8 '14 at 12:55

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