the origin of species the beak of the finch

'Now we can safely conclude that interspecies hybridization has played a critical role in the evolution of the finches, and has contributed to maintaining their genetic diversity,' says Peter Grant. 'During our field work on the Galapagos we have observed many examples of hybridization between species of Darwin's finches but the long-term evolutionary effects of these hybridizations have been unknown,' say Peter and Rosemary Grant, Princeton University, who know more about the biology of the Darwin's finches than anyone else in the world after carrying out field work on the Galapagos during a 40 year period. The scientists could even trace clear signs of hybridization between a warbler finch and the common ancestor of tree and ground finches that must have occurred about a million year ago. One important insight was that gene flow between species has played a prominent role throughout the evolutionary history of the Darwin's finches. Multiple individuals of each species were analyzed and for some species birds from up to six different islands were sampled to study variation within and between islands. 'We have now sequenced 120 birds including all known species of Darwin's finches, as well as two closely related species in order to study their evolutionary history,' explains Sangeet Lamichhaney PhD student and shared first author on the paper.

Changes in the size and form of the beak have enabled different species to utilize different food resources such as insects, seeds, nectar from cactus flowers as well as blood from iguanas, all driven by Darwinian selection. During the time that has passed the Darwin's finches have evolved into 15 recognized species differing in body size, beak shape, song and feeding behaviour. Their common ancestor arrived on the Galapagos about two million years ago. Darwin's finches are a classical example of an adaptive radiation.

The origin of species the beak of the finch