AP BIOLOGY

Detailed explanation-1: -Adaptation is manifest largely as evolutionary changes in beak morphology, and is driven by natural selection for feeding ecology, (Gibbs & Grant 1987) and by selection against interspecific competition (Schluter et al. 1985).

Detailed explanation-2: -We show that Darwin’s finches on a Galapagos island underwent two evolutionary changes after a severe El Nino event caused changes in their food supply. Small beak sizes were selectively favoured in one granivorous species when large seeds became scarce.

Detailed explanation-3: -Evolution in Darwin’s finches is characterized by rapid adaptation to an unstable and challenging environment leading to ecological diversification and speciation. This has resulted in striking diversity in their phenotypes (for instance, beak types, body size, plumage, feeding behavior and song types).

Detailed explanation-4: -Key factors in their evolutionary diversification are environmental change, natural selection, and cultural evolution. A long-term study of finch populations on the island of Daphne Major has revealed that evolution occurs by natural selection when the finches’ food supply changes during droughts.

Detailed explanation-5: -The food available on the different islands varied and the finches had to evolve beaks which could take advantage of the food supplies available to them. These birds, although nearly identical in all other ways to mainland finches, evolved different beaks. Their beaks adapted to the type of food that they ate.