How would Darwin explain the origin of over a dozen different species of finches on the Galapagos Islands, when it was thought that only one species was the original parent species for all?

Question

What will be an ideal response?

Answer 1

At the heart of Darwin's explanation is his theory of natural selection, which states that within any species there is a natural variation for any given trait (in this case, beak size and shape). Once the parent species began to populate the various islands in the Galapagos, there were different selective forces at work on the finches because each island had slightly different physical parameters (for example, different temperatures and precipitation resulting in different vegetation). In the process of natural selection, individuals in a population that are most fit for that particular condition survive and leave more offspring, causing their adaptations to become more common in the population. Therefore, on the more desert/dry islands where smaller seeds were prevalent, finches that had smaller beaks were better suited and flourished. After several generations, the population on this island became mostly small-beaked finches. On one island, a species of finch actually evolved to use small sticks or cactus spines to prod insects from crevices and holes in trees, as there were very few seeds on this island.