• DOI:10.1038/416323a
• Corpus ID: 4432142

Reduced adaptation of a non-recombining neo-Y chromosome

@article{Bachtrog2002ReducedAO,
  title={Reduced adaptation of a non-recombining neo-Y chromosome},
  author={Doris Bachtrog and Brian Charlesworth},
  journal={Nature},
  year={2002},
  volume={416},
  pages={323-326}
}

• D. Bachtrog, B. Charlesworth
• Published 21 March 2002
• Biology
• Nature

Sex chromosomes are generally believed to have descended from a pair of homologous autosomes. Suppression of recombination between the ancestral sex chromosomes led to the genetic degeneration of the Y chromosome. In response, the X chromosome may become dosage-compensated. Most proposed mechanisms for the degeneration of Y chromosomes involve the rapid fixation of deleterious mutations on the Y. Alternatively, Y-chromosome degeneration might be a response to a slower rate of adaptive evolution, caused by its lack of recombination. Here we report patterns of DNA polymorphism and divergence at four genes located on the neo-sex chromosomes of Drosophila miranda. We show that a higher rate of protein sequence evolution of the neo-X-linked copy of Cyclin B relative to the neo-Y copy is driven by positive selection, which is consistent with the adaptive hypothesis for the evolution of the Y chromosome. In contrast, the neo-Y-linked copies of even-skipped and roundabout show an elevated rate of protein evolution relative to their neo-X homologues, probably reflecting the reduced effectiveness of selection against deleterious mutations in a non-recombining genome. Our results provide evidence for the importance of sexual recombination for increasing and maintaining the level of adaptation of a population.