Heat brings out the central bearded dragon鈥檚 feminine side (Image: Arthur Georges)
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IF YOU can鈥檛 stand the heat, change sex. Male lizards from Australia become females in hot weather.
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Male central bearded dragons () have ZZ sex chromosomes; females have ZW. But we know from studies in the lab that ZZ eggs exposed to temperatures over 32 掳C can hatch as females.
Now at the University of Canberra, Australia, and her team have discovered that this happens in the wild too. Of 131 lizards they caught, 11 females had ZZ chromosomes.
What鈥檚 more, the ZZ females laid almost twice as many eggs as ZW females. All of these eggs would be ZZ, since both the mother and father were. 鈥淭hey鈥檝e lost a whole chromosome in one generation,鈥� says Holleley.
The ZZ mothers also passed on a propensity to change sex: their embryos switch from male to female at lower temperatures than eggs from ZW mothers. In fact, sex was determined solely by temperature, not chromosomes.
This means global warming could cause the sex switching to snowball 鈥� possibly putting the species at greater risk of extinction ().
This article appeared in print under the headline 鈥淗eat is on for sex-change lizard鈥�