"For years, this has been the classic textbook example of rapid evolution," said David Skelly, an ecologist and rapid evolution researcher at Yale University, referring to the competitive pressure on G. fortis by the larger beaked G. magnirostris.
"When I was a student, (Grant’s) work was sometimes taught as the exception to the rule," said Skelly.
That is, normally evolution is thought of as slow and gradual in large animals like fish, birds, reptiles and mammals. Beak sizes changing measurably in just decades seemed awfully fast. The Galapagos finches were considered an extreme case of quick evolution caused by an extreme environment.
"Now it appears that the Grants' work shows a pattern that is likely to be widespread," said Skelly, who has studied rapid evolution of amphibians in response to global warming. "Environmental changes severe enough to cause sharp population declines, as seen with the finches, are also selection events."
As more and more species undergo the stresses of climate change, more cases of rapid evolution can be expected, Skelly said. It’s not likely to save most species facing the climatic bottleneck, of course, but it does give a few a fighting chance, he explained.
"I don't think there is any reason to suspect this is an unsual occurrance," said biologist Richard Shine of the University of Sydney in Australia.
Shine has charted the rapid evolution of longer legs in invasive cane toads in Australia, as well as adaptive changes in native snakes where the toads have invaded over the past few decades.
We'd see more evidence of rapid evolution if there was more support for long-term field studies like that of the Grants' 30-year work on the finches, he said. "It's incredibly difficult to maintain these long-term studies."
