Evolutionary anthems: the songs of Darwin finches might be responsible for the group rapid speciation

Natural History, Oct, 2003 by Adam Summers

One of the chief roles of calls among songbirds is to find mates, and that takes me back to the topic of sympatric speciation. When that first population of generalist finches invaded the Galapagos, natural variation in beak size among individuals would have made the tougher seeds an accessible food item for some of the animals but not for others. Because song pitch and beak strength are interrelated, those birds would also have sung a slightly simpler, deeper song than their smaller-beaked brethren. Many female birds prefer males with a familiar call--their own--and so heavy-beaked females would have preferred the song of heavy-beaked males. The link between song and food could thereby lead to segregated mating within a population, even though all the individuals in the population could freely mix.

Ah, the sweet sound of evolution in action!

Adam Summers (asummers@uci.edu) is an assistant professor of ecology and evolutionary biology at the University of California, Irvine.