Reptile news!

[herpencounter]

(June 4, 2009) — Whether baby lizards will turn out to be male or female is a more complicated question than scientists would have ever guessed, according to a new report published online on June 4th in Current Biology. The study shows that for at least one lizard species, egg size matters.

"We were astonished," said Richard Shine of the University of Sydney. "Our studies on small alpine lizards have revealed another influence on lizard sex: the size of the egg. Big eggs tend to give girls, and small eggs tend to give boys. And if you remove some of the yolk just after the egg is laid, it's likely to switch to being a boy, even if it has female sex chromosomes; and if you inject a bit of extra yolk, the egg will produce a girl, even if it has male sex chromosomes."

In many animals, the sex of offspring depends on specialized sex chromosomes. In mammals and many reptiles, for instance, males carry one X and one Y chromosome, while females have a pair of X chromosomes. In contrast, animals such as alligators depend on environmental cues like temperature to set the sex of future generations.

The new findings add to evidence that when it comes to genetic versus environmental factors influencing sex determination, it doesn't have to be an either/or proposition. In fact, Shine and his colleagues earlier found in hatchlings of the alpine-dwelling Bassiana duperreyi that extreme nest temperatures can override the genetically determined sex, in some cases producing XX boys and XY girls. His group had also noticed something else: large lizard eggs were more likely to produce daughters and small eggs to produce sons.

Despite the correlation, Shine said he had assumed that the association was indirect. In fact, his colleague Rajkumar Radder conducted studies in which he removed some yolk from larger eggs, more likely to produce daughters, to confirm that assumption.

"We were confident that there would be no effect on hatchling sex whatsoever," Shine said. "When those baby boy lizards started hatching out, we were gob-smacked."

Shine thinks there will be much more to discover when it comes to lizard sex determination.

"I suspect that the ecology of a species will determine how it makes boys versus girls, and that our yolk-allocation effect is just the tip of a very large iceberg," he said.

:main_thumbsup:

 

[corvettefan]

So if I found eggs today in my leo's tank, and one was bigger than the other, I could say the big one was a female, and the small one was a male?

 

[herpencounter]

So if I found eggs today in my leo's tank, and one was bigger than the other, I could say the big one was a female, and the small one was a male?

Apparently. But with the temps we make them what we want... Might be an interesting experiment to incubate them at 86, and mark big eggs and small eggs, and see what you get.

 

[chachasushi]

My LVP laid a GIANT egg- that's a big girl! She's being incubated female anyway though. That was a very interesting article.

 

[liljenn]

Apparently. But with the temps we make them what we want... Might be an interesting experiment to incubate them at 86, and mark big eggs and small eggs, and see what you get.

I think that would be an interesting study, if you get clutches where one is obviously bigger than the other (maybe weigh them???)

Anyway, thanks for the interesting read!:main_thumbsup:

 

[EchoPet]

Interesting article. I'm a little confused on some of the wording though. It says that the findings about temperature where with Bassiana duperreyi, but it's not clear to me whether the comments about big eggs vs small eggs was just in reference to that species or others as well. I think the comments earlier indicate that it was just with the one species, but I wonder if they tried this with any others. Still pretty neat though!

 

[herpencounter]

The study shows that for at least one lizard species, egg size matters.

You would usually expect more then just one species. Still interesting.

 

[EchoPet]

Ah ok, sorry it's late and I wasn't reading carefully enough. I still wonder if they tried to find similar results with other species but so far just the one had those results.

 

[mainelygeckos]

That is a very interesting read. Any of you out there that breed now plan to try outthis study? Would be interesting to find out if it is the same with leos

 

[thestack510]

Interesting article. Thanks for posting.