“High temperatures can make an Australian lizard that is genetically male develop into a female. The finding throws new light on how sex is determined in reptiles.”
“For most reptiles, a gene on a sex chromosome triggers an embryo to develop as either a male or a female. In some species, males have an X and a Y chromosome, while females are XX, as in mammals. In other species such as birds, males are ZZ, while females are ZW.
But for a third group, which includes all crocodiles, alligators and marine turtles, temperature, rather than a gene on a sex chromosome, triggers either male or female differentiation. Extreme low or high temperatures generally lead to more females.
Now, a team led by Alex Quinn at Canberra University in Australia, has found that the central bearded dragon (Pogona vitticeps) is susceptible to both types of sex trigger, and that temperature can override its genetic gender.”