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Genomic Evolution of Bird Sex Chromosomes

Session Information

Birds are the most speciose and arguably the most successful terrestrial vertebrate with tremendous phenotypic diversities that facilitate their inhabitation throughout the planet. They can be divided into two clades: Paleognathae (tinamous and flightless ratites), and Neoganathae with over half of the latter, and also of all bird species as passerines. All birds have independently evolved ZW sex chromosomes, in contrast to the XY of mammals. I will present here progress from our recent genomic studies of sex chromosomes of 15 paleognaths and 11 passerines. We found almost all ratites have long pseudoautosomal regions (PAR) that span over 2/3 the entire sex chromosome length and have homologous recombination. Interestingly, a similar pattern has also been found in half of the tinamous species with a much higher mutation rate than the ratites. Due to the ancestral rapid speciation, PAR and also suppression of recombination evolved independently within individual lineages/species, presenting a great diversity of PAR lengths and W-linked gene repertoire. On the other hand, all the studied passerines have short PARs and shared stratified regions of recombination suppression between sex chromosomes. Given the extensive sexual selection in species like bird-of-paradise, it is surprising to find that majorities of studied passerines have retained substantial (>70) W-linked genes that are conserved across species. These results illuminate diversified mode of sex chromosome evolution of birds, and also the distinctive mutational and selective forces that underlie the evolution of ZW and XY systems.

Jul 05, 2018 10:30 AM - 11:00 AM(UTC)
Venue : 2B9 - Building 2
20180705T1030 20180705T1100 UTC Genomic Evolution of Bird Sex Chromosomes

Birds are the most speciose and arguably the most successful terrestrial vertebrate with tremendous phenotypic diversities that facilitate their inhabitation throughout the planet. They can be divided into two clades: Paleognathae (tinamous and flightless ratites), and Neoganathae with over half of the latter, and also of all bird species as passerines. All birds have independently evolved ZW sex chromosomes, in contrast to the XY of mammals. I will present here progress from our recent genomic studies of sex chromosomes of 15 paleognaths and 11 passerines. We found almost all ratites have long pseudoautosomal regions (PAR) that span over 2/3 the entire sex chromosome length and have homologous recombination. Interestingly, a similar pattern has also been found in half of the tinamous species with a much higher mutation rate than the ratites. Due to the ancestral rapid speciation, PAR and also suppression of recombination evolved independently within individual lineages/species, presenting a great diversity of PAR lengths and W-linked gene repertoire. On the other hand, all the studied passerines have short PARs and shared stratified regions of recombination suppression between sex chromosomes. Given the extensive sexual selection in species like bird-of-paradise, it is surprising to find that majorities of studied passerines have retained substantial (>70) W-linked genes that are conserved across species. These results illuminate diversified mode of sex chromosome evolution of birds, and also the distinctive mutational and selective forces that underlie the evolution of ZW and XY systems.

2B9 - Building 2 GSA2018_APCC6 GSACC62018@canberra.edu.au
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