Climate change turns male lizards into females!

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Climate-induced change of male dragon lizards into females, occurring in the wild, has been confirmed for the first time, according to recent research published in the international journal Nature. A warm climate can now be officially considered emasculating in reptiles.

It’s been known since long that temperature has sex-transforming effect on some reptiles. In case of Australian bearded dragon lizards, as temperature goes beyond to 37 degree Celsius, the sex determining process can switch to temperature determined process and resulting into 16:1 (female: male) ratio.

Professor Arthur Georges from University of Canberra explained, “We had been able to demonstrate that when exposed to high temperature, the male embryos can turn into female embryos” and now recently they have explained that the naturally transforming individuals are more fertile. The team used data from both controlled breeding experiments, as well as field data from 131 adult lizards. This data concluded that some female lizards from warmer temperatures actually had male chromosomes — and, moreover, those female lizards with male chromosomes produced more eggs.

A new breeding line can be established by mating the sex reversed female with normal males in which temperature solely determines sex. The researchers also found that sex reversed females who had male chromosomes are more fertile and laid more eggs. So in a way one can argue that the Father lizards make better mothers.

Distinguished Professor Arthur Georges and Dr Clare Holleley hold two bearded dragons inside their lab at the University of Canberra's Institute of Applied Ecology. Credit: Michelle McAulay
Distinguished Professor Arthur Georges and Dr Clare Holleley hold two bearded dragons inside their lab at the University of Canberra’s Institute of Applied Ecology.
Credit: Michelle McAulay

A population studied by the team is on the sheer drop off making the change from genetic sex determination to temperature-based sex determination — all which is required is for the climate to boost by just a fraction of a degree resulting in a heavily female-skewed population. “Once they 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,” the authors concluded.

“The mechanisms that establish sex have a profound impact on the evolution and persistence of all sexually reproducing species,” Professor Georges said. The more we learn about them, the better-equipped we’ll be to predict evolutionary responses to climate change.

For more, read here.