- Not Exactly Rocket Science
Sex runs hot and cold – why does temperature control the gender of Jacky dragons?
Among Jacky dragons, females are both hot and cool, while males are merely luke-warm. For this small Australian lizard, sex is a question of temperature. If its eggs are incubated at low temperatures (23-26ºC) or high ones (30-33ºC), they all hatch as females; anywhere in the middle, and both sexes are born.
This strategy – known as ‘temperature-dependent sex determination (TSD) – seems unusual to us, with our neat gender-assigning X and Y chromosomes, but it’s a fairly common one for reptiles. Crocodiles are all-male at high temperatures and all-female at low ones, while turtles flip the rules around and produce more males in cooler climes. Assigning gender based on temperature is not uncommon but it is nonetheless puzzling.