Initiation of sex chromosome evolution

Range >130 Ma (million years ago)
Organism Birds
Reference Yazdi HP, Ellegren H. Old but not (so) degeneratedslow evolution of largely homomorphic sex chromosomes in ratites. Mol Biol Evol. 2014 Jun31(6):1444-53. doi: 10.1093/molbev/msu101. abstractPubMed ID24618361
Comments Abstract: "Degeneration of the nonrecombining chromosome is a common feature of sex chromosome evolution, readily evident by the presence of a pair of largely heteromorphic chromosomes, like in eutherian mammals and birds. However, in ratites (order Palaeognathae, including, e.g., ostrich), the Z and W chromosomes are similar in size and largely undifferentiated, despite avian sex chromosome evolution was initiated > 130 Ma. To better understand what may limit sex chromosome evolution, [investigators] performed ostrich transcriptome sequencing and studied genes from the nonrecombining region of the W chromosome."
Entered by Uri M
ID 112865