In vertebrates, sex can be determined either genetically or by temperature, but the evolutionary causes of this variation remain unknown. These authors show how live-bearing lizards at different climatic extremes of their range differ in their sex-determining mechanisms, with temperature-dependent sex determination in the lowlands and genotypic sex determination at higher altitudes. Their results establish an adaptive explanation for intra-specific divergence in sex-determining systems driven by phenotypic plasticity and ecological selection.
- Ido Pen
- Tobias Uller
- Erik Wapstra
