Phylogeny and sex chromosome evolution of Palaeognathae

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

11 Scopus Citations
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  • Zongji Wang
  • Xiaoman Xu
  • Christopher Witt
  • Yuan Deng
  • Guangji Chen
  • Guanliang Meng
  • Shaohong Feng
  • Luohao Xu
  • Tamas Szekely
  • Guojie Zhang
  • Qi Zhou


Original languageEnglish
Pages (from-to)109-119
Journal / PublicationJournal of Genetics and Genomics
Issue number2
Online published13 Jul 2021
Publication statusPublished - Feb 2022
Externally publishedYes


Many paleognaths (ratites and tinamous) have a pair of homomorphic ZW sex chromosomes in contrast to the highly differentiated sex chromosomes of most other birds. To understand the evolutionary causes for the different tempos of sex chromosome evolution, we produced female genomes of 12 paleognathous species and reconstructed the phylogeny and the evolutionary history of paleognathous sex chromosomes. We uncovered that Palaeognathae sex chromosomes had undergone stepwise recombination suppression and formed a pattern of “evolutionary strata”. Nine of the 15 studied species' sex chromosomes have maintained homologous recombination in their long pseudoautosomal regions extending more than half of the entire chromosome length. We found that in the older strata, the W chromosome suffered more serious functional gene loss. Their homologous Z-linked regions, compared with other genomic regions, have produced an excess of species-specific autosomal duplicated genes that evolved female-specific expression, in contrast to their broadly expressed progenitors. We speculate such “defeminization” of Z chromosome with underrepresentation of female-biased genes and slow divergence of sex chromosomes of paleognaths might be related to their distinctive mode of sexual selection targeting females rather than males, which evolved in their common ancestors.

Research Area(s)

  • Comparative genomics, Paleognaths, Sex chromosome evolution, Sexual selection

Citation Format(s)

Phylogeny and sex chromosome evolution of Palaeognathae. / Wang, Zongji; Zhang, Jilin; Xu, Xiaoman et al.
In: Journal of Genetics and Genomics, Vol. 49, No. 2, 02.2022, p. 109-119.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review