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It is known that Australian bearded dragon lizards can change gender in the egg. Incubation temperatures of some reptiles can influence the sex of the babies. Unlike mammals, including humans, where the sex determination is purely based on the sex chromosomes inherited from the parents, some fish, amphibians and certain reptiles, included the dragons, have this other mode of sex determination. And when the temperature rises above 36ºC, this temperature mode of sex determination overrides the genetic one. This means that lizards that are genetically male, are physically female. Dr Clare Holleley, at University of Canberra in Australia, has found these ‘sex reversed females’ breeding in the wild. They lay more eggs and all the offspring, provided the temperature remains hot during incubation, tend to be physically female, despite being genetically male. The implications of this ‘feminisation of these lizard populations and a warming climate could become a concern.

(Photo caption: The Australian central bearded dragon ©Arthur Georges/University of Canberra, Australia via AP)