Evolution of sex determining genes in fish
Résumé
Fish have an exceptionally high diversity of sex determination systems including environmental- and genetic-based determinism. Master sex determining (MSD) genes that control genetic sex-determination also evolve extremely rapidly in fish, providing a window to understand the evolutionary mechanisms and processes of sex chromosome formation. Despite this high turnover, most of the currently known MSD genes are classical “usual suspects”, i.e., genes that evolved from downstream sex differentiation gene network. Intriguingly, fish also provide the only known exception to this “usual suspects” rule: a duplicate of an immune-related gene is the conserved salmonid MSD gene, unraveling further flexibility.