Oxford University zoologists have discovered that a single species of Tasmanian lizard has evolved to give precedence to a certain gender of offspring, dependant on the current climate.
The animal is the snow skink, a small lizard that lives throughout Tasmania and gives birth to live young.
Dr Tobias Uller et al, of Oxford University’s Department of Zoology, discovered that at high altitude, the skinks gave birth to an equal ratio of boys and girls. But at lower altitudes, in the lowlands of Tasmania and close to sea level, the skinks have been shown to produce mainly sons during times of cool temperatures and cloudy skies, but favour daughters when its sunny and warm.
It’s thought to be because female skinks rely on a large body size to survive, so by being born in the warmer, early seasons they’ll get a “head start”. Male skinks are less dependant on building up a large body, so they can be born in colder temperatures and develop more slowly.
“‘What we have found is that this single species of lizard has evolved two different ways of determining the sex of its offspring — one based on genetics, the other controlled by temperature,” Uller said. “Our results suggest that temperature-dependent sex determination can evolve in cold-blooded animals, whenever there is an advantage in offspring of a particular sex being born or hatched earlier.”
The results of the research help clarify just how important climate is on certain species, and how elements such as temperature can have a huge impact on the fundamental biology of animals.
Another animal that gets picky about gender is the Gouldian finch. Mismatched birds (determined by the colours of their head feathers) produce less healthy female chicks, so bird in genetically troubled relationships compensate by having more male babies in their brood.