Rabosky and Matute created computer models to carry out the comparison, and the results surprised them.
"We found no evidence that these things are related. The rate at which genetic reproductive barriers arise does not predict the rate at which new species form in nature," Rabosky said. "If these results are true more generallywhich we would not yet claim but do suspectit would imply that our understanding of species formation is extremely incomplete because we've spent so long studying the wrong things, due to this erroneous assumption that the main cause of species formation is the formation of barriers to reproduction.
"To be clear, reproductive barriers are still important on some level. All sorts of plants and animals live together in the same place, which couldn't happen without reproductive barriers. But our results question whether genetic reproductive barriers played a major role in how those species formed in the first place."
While speciation is often defined as the evolution of reproductive isolation, the new findings suggest that a broader definition may be needed, Rabosky and Matute conclude.
Over the last decade or so, the pursuit of the genetic underpinnings of speciation has led to reports on the discovery of a handful of "speciation genes," defined as genes that contribute to reproductive isolation between species. The studies include a 2008 Nature paper that reported the first speciation gene in a mammal.
But if the findings of Rabosky and Matute prove to be more widely applicable to other organisms, speciation genes probably play a minimal role in the formation of species, they said.
"The whole enterprise of finding 'speciation ge
|Contact: Jim Erickson|
University of Michigan