Final answer:
The diversity in finch beak shapes observed by Darwin in the Galápagos Islands serves as evidence of adaptive radiation and natural selection, where different beak types evolved to handle various food sources in the finches' respective habitats.
Step-by-step explanation:
The diversity in the type of beaks of finches on the Galápagos Islands provides evidence for adaptive radiation and natural selection. Darwin observed that beak shape varies among finch species, indicating that the beaks of an ancestral species adapted over time to enable the finches to acquire different food sources.
For example, the seed-eating birds have thick, stronger beaks to crack open hard nuts, while nectar-eating birds have long, slender beaks ideal for reaching into flowers, and insect-eating birds have pointed beak shapes suitable for capturing insects. This illustrates how finches likely dispersed from one parent species and underwent evolutionary changes due to different feeding habits in their respective environments, leading to diverse beak shapes. Each beak shape is well-suited to the specific food sources available in their habitat.