Form and Function

Charles Darwin observed in his journal that finches living on different Galapagos Islands had different beaks. He also observed that the environment on each of four islands was quite different from the environment on the other three islands; in particular, the type of food available to the finches was different on each island. He developed an hypothesis that the finches had all been the same at one time, (probably blown over from the coast of South America), with some variations in their beaks which made some beak types better adapted to the food on each island and so the birds with those beaks survived and reproduced and the others did not on that particular island with its particular type of food.These are an example of four different types of beaks found in finches living in the four different islands.

http://www.stem.neu.edu/programs/re-seed/activities-and-labs/natural-selection-bird-beak/