Many Paleognaths have a pair of homomorphic ZW sex chromosomes (male ZZ, female ZW) in contrast to the highly differentiated sex chromosomes of most other birds. To understand the evolutionary causes for different tempo of sex chromosome evolution, Qi Zhou’s group produced female genomes of 12 Paleognathous species. They found that Palaeognathae sex chromosomes harbor a great diversity among species in their composition of pseudoautosomal regions, recombination suppression, degree of functional gene loss and gene traffic. They speculated these patterns might be related to their distinctive mode of paternal-only offspring care.
