Genetic mechanisms of sex determination

Abstract

Sex determination, although crucially important for the survival of a species, is arguably the least conserved mechanism in evolution and is instead one of the most variable developmental pathways. There are two main mechanisms of sex determination: genetic (GSD) and environmental sex determination (ESD). Amongst vertebrates, many reptiles such as crocodiles and turtles determine sex by ESD, whereas birds and mammals, including human display GSD. GSD can be further subdivided into those for which the males are heterogametic, that is, an XX-XY system, and those with heterogametic females, that is, ZZ-ZW system. Here, we review genetic mechanisms of sex determination.