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.

Zongji Wang;Jilin Zhang;Xiaoman Xu;Christopher Witt;Yuan Deng;Guangji Chen;Guanliang Meng;Shaohong Feng;Luohao Xu;Tamas Szekely;Guojie Zhang;Qi Zhou

MOE Laboratory of Biosystems Homeostasis and Protection and Zhejiang Provincial Key Laboratory for Cancer Molecular Cell Biology,Life Sciences Institute,Zhejiang University,Hangzhou,Zhejiang 310058,China;Department of Neuroscience and Developmental Biology,University of Vienna,Vienna 1090,Austria;Institute of Animal Sex and Development,Zhejiang Wanli University,Ningbo,Zhejiang 315100,China;BGI-Shenzhen,Beishan Industrial Zone,Shenzhen 518083,China;Department of Medical Biochemistry and Biophysics,Karolinska Institutet,SE-171 77 Stockholm,Sweden;Department of Biology and the Museum of Southwestern Biology,University of New Mexico,Albuquerque,NM 87131,USA;State Key Laboratory of Biocontrol,Department of Ecology,School of Life Sciences,Sun Yat-sen University,Guangzhou,Guangdong 510275,China;Milner Center for Evolution,Department of Biology and Biochemistry,University of Bath,Bath BA1 7AY,UK;State Key Laboratory of Genetic Resources and Evolution,Kunming Institute of Zoology,Chinese Academy of Sciences,Kunming,Yunnan 650223,China;Section for Ecology and Evolution,Department of Biology,University of Copenhagen,DK-2100 Copenhagen,Denmark;Center for Excellence in Animal Evolution and Genetics,Chinese Academy of Sciences,Kunming,Yunnan 650223,China;Center for Reproductive Medicine,The 2nd Affiliated Hospital,School of Medicine,Zhejiang University,Hangzhou,Zhejiang 310052,China

遗传学报

[1]Zongji Wang;Jilin Zhang;Xiaoman Xu;Christopher Witt;Yuan Deng;Guangji Chen;Guanliang Meng;Shaohong Feng;Luohao Xu;Tamas Szekely;Guojie Zhang;Qi Zhou-.Phylogeny and sex chromosome evolution of Palaeognathae)[J].遗传学报,2022(02):109-119

Palaeognathae,paleognaths,ratites,tinamous,tempos,paleognathous,pseudoautosomal,defeminization,underrepresentation

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