The evolution of restricted recombination in sex chromosomes

Trends Ecol Evol. 2009 Feb;24(2):94-102. doi: 10.1016/j.tree.2008.09.010. Epub 2008 Dec 25.


In species with separate sexes, sex determination often has a genetic basis, and in a wide diversity of taxa a pair of cytologically distinguishable 'sex chromosomes' are found such that the chromosome complements of males and females differ (males are often XY and females XX, but sometimes females are ZW whereas males are ZZ). Recent evidence from sequences of sex-linked genes confirms classical genetic evidence that these chromosomes are a homologous pair, evolved from a normal chromosome pair, between which recombination stopped. We discuss why sex chromosomes evolve reduced recombination and why different parts of the chromosomes stopped recombining at different times, and outline some of the consequences of suppressed recombination, including the evolution of chromosome heteromorphism.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Evolution, Molecular*
  • Genes, Mating Type, Fungal / physiology
  • Humans
  • Recombination, Genetic*
  • Sex Chromosomes / physiology*
  • Sex Determination Processes