Slimy hagfish help solve mysteries of genome duplication

With an eyeless face and slimy body that only a mother could love, hagfish fascinate many biologists. These eel-like, jawless vertebrates have now helped scientists solve a major evolutionary mystery: When did vertebrate genomes double in size and what happened as a result? It’s long been known that in the past, various plants and animals duplicated all their genes in one fell swoop. By sequencing hagfish genomes for the first time, two teams working independently have clarified when two of these genomic upheavals occurred in the early history of vertebrates. In addition to helping explain some of the hagfish’s unusual biology, the sequencing successes, reported last week in Nature Ecology & Evolution and in a recent preprint accepted at Nature , challenge the widely held idea that genome doubling drives species diversification. The hagfish genomes also indicate that early vertebrates were more complex than originally thought, the teams conclude. “This work solves several major conundrums in understanding how vertebrates evolved,” says John Postlethwait, an evolutionary developmental biologist at the University of Oregon who in 1998 was one of the first to suggest genome duplications were important for evolution . Among vertebrates, hagfish are outliers. Not only do they lack eyes and jaws, but they also have no paired fins or legs. And instead of being bony, their skeleton is cartilaginous. They’re grouped togethe...
Source: ScienceNOW - Category: Science Source Type: news