Whole-genome sequence of a flatfish provides insights into ZW sex chromosome evolution and adaptation to a benthic lifestyle

Nat Genet. 2014 Mar;46(3):253-60. doi: 10.1038/ng.2890. Epub 2014 Feb 2.


Genetic sex determination by W and Z chromosomes has developed independently in different groups of organisms. To better understand the evolution of sex chromosomes and the plasticity of sex-determination mechanisms, we sequenced the whole genomes of a male (ZZ) and a female (ZW) half-smooth tongue sole (Cynoglossus semilaevis). In addition to insights into adaptation to a benthic lifestyle, we find that the sex chromosomes of these fish are derived from the same ancestral vertebrate protochromosome as the avian W and Z chromosomes. Notably, the same gene on the Z chromosome, dmrt1, which is the male-determining gene in birds, showed convergent evolution of features that are compatible with a similar function in tongue sole. Comparison of the relatively young tongue sole sex chromosomes with those of mammals and birds identified events that occurred during the early phase of sex-chromosome evolution. Pertinent to the current debate about heterogametic sex-chromosome decay, we find that massive gene loss occurred in the wake of sex-chromosome 'birth'.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Physiological / genetics
  • Animals
  • DNA / genetics
  • Dosage Compensation, Genetic
  • Evolution, Molecular*
  • Female
  • Flatfishes / genetics*
  • Flatfishes / physiology
  • Genome
  • Male
  • Molecular Sequence Data
  • RNA / genetics
  • Sex Chromosomes / genetics*
  • Sex Determination Processes


  • RNA
  • DNA

Associated data

  • GENBANK/AGRG00000000
  • SRA/SRA047922
  • SRA/SRA122228