When Charles Darwin traveled to the Galapagos Islands almost 200 years ago as a gentleman naturalist, he used the power of observation to develop his theory that species evolve over time.
Miles is professor and chair of biological sciences in the College of Arts and Sciences at Ohio University. He and co-authors, Ricklefs of the University of Missouri-St. Louis and Losos of Washington University, set out to study existing hypotheses of adaptive radiation. The results suggested a new alternative possibility.
"But an alternative possibility is that morphological diversification in the most diverse clades resulted from the same underlying process of evolution that is common, at least in a statistical sense, to all clades in the comparison group," Miles added.The researchers used an extensive data set on passerine bird morphology accumulated by Ricklefs for possible answers, taking several different approaches to test the conflicting theories.
"Several groups of birds stand out as classic cases of island radiations, including clades restricted to single islands as well as to island archipelagoes," Miles said."Among the most celebrated of these are the Darwin finches of the Galapagos Islands, which have been the subject of many analyses of evolutionary diversity. Other celebrated island clades include the Hawaiian honeycreepers, the birds-of-paradise of New Guinea, the vangas of Madagascar, and the West Indian tanagers.