Temperature-Dependent Sex Determination in Reptiles

The sex of a reptile [6] embryo partly results from the production of sex hormones [7] during development, and one such process to produce those hormones [8] depends on temperature of the embryo's environment. The production of sex hormones [7] can result solely from genetics or from genetics in combination with the influence of environmental factors. In genotypic sex determination [9], also called genetic or chromosomal sex determination [9], an organism?s genes [10] alone determine which hormones [8] are produced. Non-genetic sex determination [9] occurs when the sex of an organism can be altered during a sensitive period of development due to external factors such as temperature, humidity, or social interactions. Temperature-dependent sex determination [9] (TSD), where the temperature of the embryo?s environment influences its sex development, is a widespread non-genetic process of sex determination [9] among vertebrates, including reptiles. All crocodilians, most turtles [11], many fish [12], and some lizards exhibit TSD.