When and how do sex-linked regions become sex chromosomes?

Research output: Contribution to journalSpecial issuepeer-review


The attention given to heteromorphism and genetic degeneration of “classical sex chromosomes” (Y chromosomes in XY systems, and the W in ZW systems that were studied first and are best described) has perhaps created the impression that the absence of recombination between sex chromosomes is inevitable. I here argue that continued recombination is often to be expected, that absence of recombination is surprising and demands further study, and that the involvement of selection in reduced recombination is not yet well understood. Despite a long history of investigations of sex chromosome pairs, there is a need for more quantitative approaches to studying sex-linked regions. I describe a scheme to help understand the relationships between different properties of sex-linked regions. Specifically, I focus on their sizes (differentiating between small regions and extensive fully sex-linked ones), the times when they evolved, and their differentiation, and review studies using DNA sequencing in non-model organisms that are providing information about the processes causing these properties.

Original languageEnglish
Pages (from-to)569-581
Number of pages12
JournalEvolution: International Journal of Organic Evolution
Issue number3
Early online date16 Feb 2021
Publication statusE-pub ahead of print - 16 Feb 2021


  • Pseudo-autosomal region (PAR)
  • partially sex-linked region
  • hemizygosity
  • genetic degeneration
  • sexual antagonism


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