Songbirds have a species quantity nearly equal to compared to animals, and so are classic models for learning mechanisms of speciation and intimate selection. Intercourse chromosomes are hotspots of both procedures, yet their history that is evolutionary in stays ambiguous. To elucidate that, we characterize feminine genomes of 11 songbird types having ZW sex chromosomes, with 5 genomes of bird-of-paradise types newly manufactured in this work. We conclude that songbird intercourse chromosomes have actually encountered at the least four actions of recombination suppression before their species radiation, creating a gradient pattern of pairwise series divergence termed ‘evolutionary strata’. Interestingly, the latest stratum probably emerged as a result of a songbird-specific rush of retrotransposon CR1-E1 elements at its boundary, or chromosome inversion in the W chromosome. The forming of evolutionary strata has reshaped the architecture that is genomic of intercourse chromosomes. We find stepwise variations of Z-linked inversions, repeat and GC contents, in addition to W-linked gene loss price which are from the chronilogical age of strata. Over 30 W-linked genes have now been preserved due to their important functions, suggested by their greater and wider phrase of orthologs in lizard compared to those of other genes that are sex-linked. We additionally look for a degree that is different of evolution of Z-linked genes vs. Autosomal genes among various types, possibly reflecting their diversified intensity of intimate selection. Our results discover the dynamic history that is evolutionary of sex chromosomes, and supply unique insights in to the mechanisms of recombination suppression.