Darwin's observations of finches indicated descent withA) no change in species. B) inheritance of large bills. C) modification in bills. D) convergence.
The answer is C. The ancestral finches from South America migrated to the various islands of the Galapagos. Each island had its own unique habitat and available food supply. In nature, competition usually ends with one species being outcompeted and possibly becoming extinct, as in Gause's principle. However, in the Galapagos, although many finches occupied the same niche, there was niche diversification that occurred. In one tree, you can have finches that feed high up, in the middle or at the ground level. Some can eat seeds, and those can be further categorized by small, medium or large seeds, some eat insects, some use a cactus needle as a tool, and some feed on the ground. Therefore, although they all descended from a common finch ancestor, over two million years of evolution, these little differences in their beak sizes and shape resulted in the many finch species seen today in the Galapagos Islands.