A role for a neo-sex chromosome in stickleback speciation

Nature. 2009 Oct 22;461(7267):1079-83. doi: 10.1038/nature08441. Epub 2009 Sep 27.


Sexual antagonism, or conflict between the sexes, has been proposed as a driving force in both sex-chromosome turnover and speciation. Although closely related species often have different sex-chromosome systems, it is unknown whether sex-chromosome turnover contributes to the evolution of reproductive isolation between species. Here we show that a newly evolved sex chromosome contains genes that contribute to speciation in threespine stickleback fish (Gasterosteus aculeatus). We first identified a neo-sex chromosome system found only in one member of a sympatric species pair in Japan. We then performed genetic linkage mapping of male-specific traits important for reproductive isolation between the Japanese species pair. The neo-X chromosome contains loci for male courtship display traits that contribute to behavioural isolation, whereas the ancestral X chromosome contains loci for both behavioural isolation and hybrid male sterility. Our work not only provides strong evidence for a large X-effect on reproductive isolation in a vertebrate system, but also provides direct evidence that a young neo-X chromosome contributes to reproductive isolation between closely related species. Our data indicate that sex-chromosome turnover might have a greater role in speciation than was previously appreciated.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Body Size
  • Crosses, Genetic
  • Female
  • Genetic Speciation*
  • Hybridization, Genetic
  • Infertility, Male / genetics
  • Japan
  • Male
  • Mating Preference, Animal
  • Oceans and Seas
  • Pacific Ocean
  • Polymorphism, Single Nucleotide
  • Quantitative Trait Loci
  • Reproduction / genetics
  • Reproduction / physiology
  • Sex Characteristics
  • Sex Chromosomes / genetics*
  • Smegmamorpha / anatomy & histology
  • Smegmamorpha / classification
  • Smegmamorpha / genetics*
  • Smegmamorpha / physiology*
  • Social Isolation
  • Y Chromosome / genetics