(a) : Development of similar adaptive functional structures in unrelated groups of organisms is called convergent evolution. It shows analogy. Examples are wings of butterfly and birds, eye of the octopus and the mammals, flippers of penguins & dolphins, etc. On the other hand, divergent evolution involves development of different functional structures along different directions due to adaptations to different needs from a common ancestral form. For example, forelimbs of vertebrates (whales, bat, cheetah, human). Though these perform different functions, they have similar anatomical structures.