Final answer:
Geographic isolation led to the diversification of Galapagos finches through adaptive radiation, where different beak shapes and feeding behaviors evolved in response to different environmental conditions and selective pressures on each island.
Step-by-step explanation:
Geographic isolation affected the diversity Darwin observed in Galapagos finches through a process known as adaptive radiation. The Galapagos Islands are a group of isolated islands with different habitats and food sources. As a result, finch populations on different islands were subjected to different environmental conditions and selective pressures, leading to the evolution of distinct beak shapes and feeding behaviors.
For example, on islands where large, hard seeds were abundant, finches with strong, thick beaks capable of breaking these seeds were more likely to survive and reproduce. On islands with small, soft seeds, finches with small beaks were favored. Over time, these beak variations led to the formation of different finch species specialized for different food sources. Therefore, geographic isolation played a crucial role in creating the diverse finch species Darwin observed on the Galapagos Islands.