Final answer:
Darwin's finches exemplify adaptive radiation, where a parent species evolved into multiple species with varying beak shapes through natural selection, each adapted to different food sources in the Galápagos Islands.
Step-by-step explanation:
Darwin discovered that a single species of finch evolved into several different species based on beak type and food availability. Adaptive radiation is exemplified by how these finches have dispersed from one parent species and undergone natural selection in different habitats, leading to adaptive changes.
This concept is highlighted by the varying beak shapes among finch species, as Darwin observed. Natural selection based on specific food sources resulted in finches with beak shapes suited to their particular diets.
Seed-eating birds evolved thicker, stronger beaks for breaking hard nuts.
Nectar-eating birds developed long beaks necessary for reaching nectar inside flowers.
Insect-eating birds have pointed beaks that are effective for catching insects.
The idea that an ancestral species' beak adapted over time to acquire different food sources is a cornerstone of Darwin's theory of evolution, which is well-demonstrated by the diverse beaks of the finches in the Galápagos Islands.