Palaeognathae includes ratite and tinamou species that are important for understanding early avian evolution.Here,we analyzed the whole-genome sequences of 15 paleognathous species to infer their demographic histories...Palaeognathae includes ratite and tinamou species that are important for understanding early avian evolution.Here,we analyzed the whole-genome sequences of 15 paleognathous species to infer their demographic histories,which are presently unknown.We found that most species showed a reduction of population size since the beginning of the last glacial period,except for those species distributed in Australasia and in the far south of South America.Different degrees of contraction and expansion of transposable elements(TE)have shaped the paleognathous genome architecture,with a higher transposon removal rate in tinamous than in ratites.One repeat family,AviRTE,likely underwent horizontal transfer from tropical parasites to the ancestor of little and undulated tinamous about 30 million years ago.Our analysis of gene families identified rapid turnover of immune and reproductionrelated genes but found no evidence of gene family changes underlying the convergent evolution of flightlessness among ratites.We also found that mitochondrial genes have experienced a faster evolutionary rate in tinamous than in ratites,with the former also showing more degenerated W chromosomes.This result can be explained by the Hill-Robertson interference affecting genetically linked W chromosomes and mitochondria.Overall,we reconstructed the evolutionary history of the Palaeognathae populations,genes,and TEs.Our findings of co-evolution between mitochondria and W chromosomes highlight the key difference in genome evolution between species with ZW sex chromosomes and those with XY sex chromosomes.展开更多
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 differen...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.展开更多
基金This study was supported by the National Natural Science Foundation of China(31671319,31722050,32061130208)Natural Science Foundation of Zhejiang Province(LD19C190001)+5 种基金European Research Council Starting Grant(grant agreement 677696)to Q.Z.the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB31020000,XDB13000000)International Partnership Program of Chinese Academy of Sciences(152453KYSB20170002)Carlsberg Foundation(CF16-0663)Villum Foundation(25900)to G.J.ZWe thank China National Genebank at BGI for contributing to the sequencing.We would like to thank Christopher C.Witt,Mariel L.Campbell and Ariel M.Gaffney from the Museum of Southwestern Biology,Gary Graves from Smithsonian Institute,Robb T.Brumfield and Donna L.Dittman from Louisiana State University Museum of Natural Science,Jack Withrow and Andy Kratter from Florida Museum of Natural History,University of New Mexico for providing bird DNA samples for this work.
文摘Palaeognathae includes ratite and tinamou species that are important for understanding early avian evolution.Here,we analyzed the whole-genome sequences of 15 paleognathous species to infer their demographic histories,which are presently unknown.We found that most species showed a reduction of population size since the beginning of the last glacial period,except for those species distributed in Australasia and in the far south of South America.Different degrees of contraction and expansion of transposable elements(TE)have shaped the paleognathous genome architecture,with a higher transposon removal rate in tinamous than in ratites.One repeat family,AviRTE,likely underwent horizontal transfer from tropical parasites to the ancestor of little and undulated tinamous about 30 million years ago.Our analysis of gene families identified rapid turnover of immune and reproductionrelated genes but found no evidence of gene family changes underlying the convergent evolution of flightlessness among ratites.We also found that mitochondrial genes have experienced a faster evolutionary rate in tinamous than in ratites,with the former also showing more degenerated W chromosomes.This result can be explained by the Hill-Robertson interference affecting genetically linked W chromosomes and mitochondria.Overall,we reconstructed the evolutionary history of the Palaeognathae populations,genes,and TEs.Our findings of co-evolution between mitochondria and W chromosomes highlight the key difference in genome evolution between species with ZW sex chromosomes and those with XY sex chromosomes.
基金supported by the National Natural Science Foundation of China (32061130208, 32170415)the Natural Science Foundation of Zhejiang Province (LD19C190001)+4 种基金the European Research Council Starting Grant (grant agreement 677696)supported by Strategic Priority Research Program of the Chinese Academy of Sciences (XDB31020000, XDB13000000)International Partnership Program of Chinese Academy of Sciences (152453KYSB20170002)Carlsberg foundation (CF16-0663)Villum Foundation (25900)。
文摘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.
