Warm Temps Triggering Gender Changes in Australia’s Dragon Lizards

PetMD Editorial
Published: July 21, 2015
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According to new research from the University of Canberra's Institute for Applied Ecology, Australia’s bearded dragon lizards are, perhaps, the ultimate chameleons. Instead of changing color, however, these lizards are changing gender.

Published in the journal Nature, the study reveals climate changes (specifically warm temperatures) are causing male lizards to transition into female lizards while in the womb.

The idea that reptiles are sensitive to temperature change — and the relationship between warm temperatures and reptilian gender — has been around for some time. Specifically in the case of Australian bearded dragon lizards, climates above 93.2 to 98.6 degrees Farenheight can cause male embryos to turn into females. This results in a greater number of female to male bearded dragons (a surprisingly high ratio of 16:1, according to research).

"This is the first time we have proved that sex reversal happens in the wild in any reptile at all," Dr. Clare Holleley, lead author of the study, told the Associated Press.

Using data from both controlled breeding experiments as well as field data from 131 adult lizards, researchers of this study found that some female lizards from warmer temps had male chromosomes, indicating that they had originally been male gendered. And, if that wasn’t surprising enough, the female lizards with Y chromosomes (the original male lizards) actually produce more eggs.

These “sex-reversed mothers,” or females that were genetic males, “laid more eggs than normal mothers," said Holleley in a media release. "So in a way, one could actually argue that dad lizards make better mums."

What Does the Future Hold for the Australian Bearded Dragon Lizard?

So, what does this mean for our reptilian friends?

Potentially, new breeding lines instigated by breeding the temperature-dependent sex-reversed females with normal males could result in a temperature-dependent system (that is, gender determined by environmental temperatures), instead of a genetic-dependent one, according to Holleley in the media release.

While it’s possible that the lizards could adapt to rising temperatures and eventually produce more males, the converse is also true.

"Once they [the Australian bearded dragon lizards] become temperature dependent, the risk is that if it keeps warming they'll produce 100 percent females and they'll be at risk of extinction, so this is a concerning finding," Professor Arthur Georges, co-author of the study, told the Sydney Morning Herald.

Image: hddigital / Shutterstock

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University of Canberra