The first people to explore the Galapagos Islands noticed that the finches there are different species than the finches living on the nearby mainland.

Question

Which most likely caused this example of speciation?
A. Unhealthy conditions on the islands caused severe mutations.
B. The birds had different mating seasons and could not interbreed.
C. Adaptation stopped on the mainland but continued on the islands.
D. The water between the mainland and islands prohibited interbreeding.

Answer 1

The most likely cause of speciation in the finches of the Galapagos Islands, as described, is:

D. The water between the mainland and islands prohibited interbreeding.

This option highlights the role of geographic isolation, which can prevent populations from interbreeding, leading to divergent evolution and the development of new species over time.