Temperature Dependent Sex Determination in Reptiles

Some reptiles such as lizards and snake determine their offspring’s sex by chromosomes. However other reptiles like turtles crocodiles and alligators determine their sex based on the environment around them at the time of the egg fertilization. Different environmental temperatures will result in different sexes. A slight change in temperature can result in dramatic differences in determining the offspring. In a given reptile one temperature rang can result in up to 100% reproduction of one sex. In-between temperatures typically result in a mix of sexes. Hormones have a large effect on the temperature sex determination as well. This is due to the enzyme Aromatase which is responsible for converting testosterone into Estrogen. In European pond turtles aromatase activity is low during low temperatures and high during high temperatures. This correlates which the turtles offspring being mainly male during low temperatures and females during high temperatures.