Answer:
Adaptive Radiation
Step-by-step explanation:
Adaptive radiation refers to the process of diversification of ancestral line into different forms that occupy diverse ecological niche. The ancestral seed eating stock of Darwin’s finches diversified according to different types of food (plants, seeds, insects, cactus etc) available. They developed type of beak adapted to that food. The geographical isolation led reproductive isolation. Hence, many species of finches on the Galápagos Islands exhibit "adaptive radiation".