[Genetic determination of sex: demonstration in animals of a phenotypic sexual inversion by temperature in the amphibian urodeles, Pleurodeles waltlii Michah].

Phenotypic males of the newt Pleurodeles waltlii were obtained from larvae of ZW genotypic females reared at 30 degrees C. They were subsequently bred with standard ZW females, and the sex-ratio of the offspring were analysed. It was found to be identical to the theoretical sex-ratio. Moreover, thelygenous WW females were detected among the offspring. These results confirm the ZZ/ZW genotypic sex determinism and irrefutably demonstrate the functional temperature sexual inversion in Pleurodeles waltlii.