Short/Long answer type questions
Give an account of Darwin's finches.

A few million years ago, one species of finch migrated to the rocky Galapagos islands from the mainland of Central or South America. From this one migrant at least 13 species of finches evolved, now known as Darwin's finches. This process in which one species gives rise to multiple species that exploit different niches is called adaptive radiation. The ecological niches exert the selection pressures that push the populations in various directions. On various islands, finch species have become adapted for different diets: seeds, insects, flowers, the blood of seabirds, and leaves. The ancestral finch was a ground-dwelling, seed-eating finch. After the burst of speciation in the Galapagos, a total of 14 species exist now. Out of these 14, three species of ground-dwelling seed-eaters; three others living on cactuses and eating seeds; one living in trees and eating seeds, and 7 species of tree-dwelling insect-eaters.