Figure 2.

Proposed model for lizard sex chromosome evolution, modified from [11]. Many Reptiles are likely to have followed the currently held view of sex chromosome evolution as proposed for vertebrates but may also involve other regulatory molecular mechanisms (e.g., epigenetic). The sex determination (sensu sex chromosomes) in genotypic sex determination (GSD) and temperature-dependent sex determination (TSD) with environment influence is bipotential and could involve polygenic or epigenetic mechanisms, hence retaining the homomorphic sex chromosomes and high diversities. MDF = Male determining factor, FDF = Female determining factor.