AMHERST, Mass. - The splitting of a species into two new species may occur in far fewer generations than scientists previously believed, according to a study led by University of Massachusetts postdoctoral researcher Andrew Hendry. Hendry, an evolutionary ecologist, conducted his study on two populations of sockeye salmon in the Pacific Northwest. The findings are published in the Oct. 20 issue of the journal, Science. His co-authors are Paul Bentzen and Thomas Quinn, both of the University of Washington, John Wenburg of the University of Montana, and Eric Volk of the Washington State Department of Fish and Game.
"There is a widely-held perception that when one population splits into two different environments, traits evolve quickly and, as a result, the two new populations become less likely to interbreed. That is, they become reproductively isolated. This process, called ecological speciation, may be one of the easiest and fastest ways that new species arise. Our results suggest that this perception may not only be correct, but in spades," said Hendry. "The classic examples of ecological speciation are for groups that have existed for 10,000 years. Even the fastest examples are for some insects over 200-400 generations. In these cases, we know reproductive isolation evolved sometime in the past, but we don't know how quickly."
In contrast, Hendry's team found evolutionary adaptations and reproductive isolation in salmon after only 12-14 generations: some 60-70 years. Specifically, scientists studied salmon introduced into Lake Washington, in Washington State, during the 1930s and 1940s. Soon after the initial introductions, two populations became established, one spawning in a river and one along a lake beach. "Sockeye salmon bury their eggs and spawn in different kinds of locations, and in a variety of environments, even in a small system such as this," Hendry explained. "When new populations bec
Contact: Elizabeth Luciano
University of Massachusetts at Amherst