Darwin's finches definition of Darwin's finches in the Free Online Encyclopedia.

Darwin's finches or Galapagos finches (gəlä`pəgōs'), species of small finches, constituting the subfamily Geospizinae of the finch family. This group of thirteen species is confined to the Galápagos Islands, except a single species found on Cocos Island, about 600 mi (960 km) northeast. Their special adaptations to various habitats were important evidence considered by Charles Darwin Darwin, Charles Robert, 1809–82, English naturalist, b. Shrewsbury; grandson of Erasmus Darwin and of Josiah Wedgwood . He firmly established the theory of organic evolution known as Darwinism .
..... Click the link for more information. in formulating the theory of evolution evolution, concept that embodies the belief that existing animals and plants developed by a process of gradual, continuous change from previously existing forms. This theory, also known as descent with modification, constitutes organic evolution.
..... Click the link for more information. ; they are a striking example of adaptive radiation adaptive radiation, in biology, the evolution of an ancestral species, which was adapted to a particular way of life, into many diverse species, each adapted to a different habitat.
..... Click the link for more information. .

Geographically isolated and without competition from similar species, these finches developed distinctive anatomy (particularly beak size and shape) and behaviors, with each species exploiting a unique feeding niche. The bill is adapted in the different species for different purposes, such as crushing seeds, pecking wood, and probing flowers for nectar. The woodpecker finch, Cactospiza pallida, an insect-eater, holds twigs and cactus spines in its beak to fish out larvae in tree cavities. Darwin proposed that the Galapagos finches evolved on the islands from a single species of finch from mainland South America. Modern methods of DNA (genetic) analysis have confirmed his insight. Darwin's finches are classified in three genera of the phylum Chordata Chordata (kôrdā`tə,–dä`–)
..... Click the link for more information. , subphylum Vertebrata, class Aves, order Passeriformes, family Fringillidae, subfamily Geospizinae.

Bibliography

See P. Grant, Ecology and Evolution of Darwin's Finches (1986).