Chimp and human Y chromosomes evolving faster than expected

MIT - MIT CAMBRIDGE, Mass. Contrary to a widely held scientific theory that the mammalian Y chromosome is slowly decaying or stagnating, new evidence suggests that in fact the Y is actually evolving quite rapidly through continuous, wholesale renovation. By conducting the first comprehensive interspecies comparison of Y chromosomes, Whitehead Institute researchers have found considerable differences in the genetic sequences of the human and chimpanzee Ys — an indication that these chromosomes have evolved more quickly than the rest of their respective genomes over the 6 million years since they emerged from a common ancestor. “The region of the Y that is evolving the fastest is the part that plays a role in sperm production,” say Jennifer Hughes, first author on the paper and a postdoctoral researcher in Whitehead Institute Director David Page’s lab. “The rest of the Y is evolving more like the rest of the genome, only a little bit faster. The chimp Y chromosome is only the second Y chromosome to be comprehensively sequenced. The original chimp genome sequencing completed in 2005 largely excluded the Y chromosome because its hundreds of repetitive sections typically confound standard sequencing techniques.