"The study of speciation has a reputation for wild speculation because every time we find a curious genetic element, we suspect it of causing speciation," says Daven Presgraves, lead author on the study and postdoctoral fellow at the University. "We know embarrassingly little about a core process in evolutionary biology, but now we've nailed down the exact sequence of a gene that we know was involved in keeping two species separated. We can see that it was natural selection that made the gene the way it is."
The study breaks ground in two ways: First, it's the first time that a gene known to be involved in speciation has had its DNA fully revealed.
Presgraves and colleagues found 20 regions that differed on the chromosomes of two species of fruit flies that were estimated to have diverged in evolution 2.5 million years ago--fairly recently in evolutionary terms. He then needed to find a gene in one of those regions that was responsible for preventing successful reproduction between the two species. If the species could reproduce, then they could swap genes back and forth and thus would not be truly separate species. Something would have to prevent the transfer of genes, and in the case of Presgraves' fruit flies, that something was the proclivity for hybrid larvae to die before maturing into adults.
He found his gene, called Nup 96, that always prevented a hybrid of the two species from living to reproduce, and he se
Contact: Jonathan Sherwood
University of Rochester