21
August 2003
Speciation: Going for a song
Though not as well known as the cuckoos, the African brood-parasitic finches are equally fascinating and differ in ways that lend insight into the evolutionary biology of both groups. In this issue, Sorenson et al. present genetic evidence for rapid sympatric speciation following host switching in one such finch, the indigobird. Sympatric speciation is the formation of descendant species from a single ancestral species in the same geographic location. Some biologists argue that it cannot happen, on the grounds that interbreeding would soon eliminate any genetic differences that might arise. The new genetic data reveal that ten distinct indigobird species evolved from a very recent common ancestor through behavioural rather than geographic isolation. In the indigobird the key behavioural components in speciation are imprinting on host song, song mimicry in males and sexual selection in the form of female choice.
Speciation by host switch in brood parasitic
indigobirds
MICHAEL D. SORENSON, KRISTINA M. SEFC & ROBERT
B. PAYNE
Nature 424, 928–931 (2003); doi:10.1038/nature01863
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