Question

darwins finches evolved on an island. what is the main reason that islands often provide good examples of evolution?
○ they have many niches.
○ they have many organisms that live on them.
○ they allow for automatic biogeographic isolation.
○ they allow for many variations to exist in species.

Explanation:

To determine the answer, we analyze each option:

• "They have many niches": Islands typically have limited niches due to smaller ecosystems, so this is incorrect.
• "They have many organisms that live on them": Islands usually have fewer organisms than larger landmasses, so this is wrong.
• "They allow for automatic biogeographic isolation": Islands are geographically isolated from the mainland, which restricts gene flow. This isolation is a key factor in evolution (e.g., Darwin’s finches), as populations can evolve independently.
• "They allow for many variations to exist in species": Variations exist in all species, and isolation (not the island itself creating variations) drives evolution on islands.

So the correct reason is biogeographic isolation.

Answer:

C. They allow for automatic biogeographic isolation.