The flippers of a whale and the fins of a fish are examples of

1. Analyze the question The question asks what evolutionary process explains the similarity between a whale's flippers and a fish's fins. Whales are mammals, and fish are not closely related to them. Both structures are used for swimming.

2. Explain the concept

• Convergent evolution: Unrelated organisms develop similar structures (analogous structures) because they adapt to similar environments or functions. The structures have different origins but the same function.
• Divergent evolution: Related organisms with a common ancestor develop different structures (homologous structures) because they adapt to different environments. Examples are the human arm, bat wing and whale flipper.
• Co-evolution: Two species influence each other's evolution, such as a flower and its pollinator.
• Continuous variation: Differences within a population that show a range of values, such as height or weight. It is not an evolutionary process.

3. Solution

• A whale is a mammal that evolved from land-dwelling ancestors. Its flipper has the bone structure of a mammalian limb.
• A fish's fin is supported by fin rays and has a different structure and origin.
• Both are adapted for swimming in water, so they perform the same function.
• Different origins with the same function means they are analogous structures, and analogous structures result from convergent evolution.

Note: if the question had compared a whale's flipper with a bat's wing or a human arm, the answer would be divergent evolution, because those are homologous structures.

4. Answer The flippers of a whale and the fins of a fish are examples of convergent evolution, which is option D.

5. Exam tip Remember: Convergent = Come together (different ancestors, similar function, analogous structures). Divergent = Differ (common ancestor, different functions, homologous structures).