Varanids sex is determined after hatching

[Ryan Wunsch]

This is not my theory, I'm not even sure who was the first person to talk about this theory.

In any case I've always thought it was a really interesting theory and I would be interested in discussing it more. I have yet to find any research that has been done on the topic.

It was discussed on Ian's Iguana Necropsy thread,
hisscanada.proboards98.com/index.cgi?board=generalscience&action=display&thread=1144609032

I thought It might be a good idea to start a specific thread for this particular topic.

Ryan

[joeysgreen]

While changing sex is known to occur in some populations of amphibians I don't think it's been documented in reptiles before. I honestly don't remember the exact species but believe it was from Africa, and it was definately a frog. If contained withen a single sex environment, some would undergo a sex change. Amphibians do have a much higher incidence of metamorphoses and tissue regeneration (salamanders can regrow whole limbs), thus this may not be possible in reptiles.

I bring all this up, to not prove anything with varanids, but to justify that the theory that varanid sex determination being determined after hatching isn't impossible. To study this, more reliable methods of sexing is necessary; methods that can be done at any age.

Another extension of this topic was DNA testing. I do believe that every species is different, and it's not as easy as detecting an X and Y chromosome as with people. Birds have been done. Iguanas have been done (the test is no longer available due to lack of interest in the test). There is no real financial backing to find a varanid DNA sexing test, but the real question is if the science is there yet.

Ian

[shawnfraser]

In 1989 Thomas A. Huff wrote a paper (Huff,T.A., (1989) An Update on Plated Lizard Reproduction at the Reptile Breeding Foundation in Captive Propagation and Husbandry of Reptiles and Amphibians Northern California Herpetological Society Special Publication #5, Edited by Ralph L. Gowen. pp.65-68.) describing the change in sex of a Smith's plated lizard (Gerrhosaurus validus) - I do not know if this taxonomic classification is still valid. In 1983 the Reptile Breeding Foundation (Tom Huff was the Director) obtained 3 adult male animals - the sexing was based on "characteristics normally indicative of a male lizard - wide, robust heads; noticeable femoral pores; and their large size." (Ibid). After four years there was "nothing that could be construed as breeding behavior", however, after autotomizing it's tail in 1986,one animal began exhibiting female characteristics - narrower head and less noticeable femoral pores. The next spring the other two lizards "had heavy exudate from their pores, and the smaller, less robust, narrower headed, less defined femoral pored individual had none." (Ibid). In 1987 they bred and the 'new' female laid eggs (4 fertile, 2 infertile) In spring of 1988 one of the other males exhibited female characteristics and two clutches of eggs were laid (6 in the first, five in the second). "Now, it is possible that our known (?) female, double-clutched, and produced all of the eggs. But, I suspect that we had single clutches from two different females."(Ibid)
Tom Huff wrote in his "Conclusion" "I have no concrete evidence for these observations...This may come about as a result of a stressful situation and as an effect of such, an effort to insure the survival of the species."(Ibid).

This is just a brief overview of the original paper. If you can find the original - or any paper by Tom Huff - read it. He was the man who coined the term 'herpetoculture' (not Phillipe de Vosjoli as is commonly asserted), and was the first person to breed 32 (!) reptile species.

[joeysgreen]

wicked stuff! I wish blood work and hormone levels were done throughout this period to follow what (and maybe how) the changes occured. Wouldn't it be odd if after accidentaly buying a pair of males, you just took one into the vet to have it's sex changed!?!

Ian