The Galápagos finches collected by Darwin are thought to have descended from a very small parent population. Different species of finches that are confined to only one or two islands most likely arose by __________.

• A. sympatric speciation
• B. gene flow
• C. polyploidy
• D. hybridization
• E. allopatric speciation

Answer: (E)

Verified step by step guidance

1. Understand the concept of allopatric speciation: It occurs when a population is divided by a geographical barrier, leading to the formation of new species due to the isolation and different environmental pressures.
2. Consider the geographical context of the Galápagos Islands: Each island can act as a geographical barrier, isolating finch populations from one another.
3. Recognize that isolation prevents gene flow between populations: This lack of gene flow allows populations to evolve independently.
4. Identify the role of natural selection and genetic drift: These mechanisms can lead to differences in traits that are advantageous in the specific environments of each island.
5. Conclude that the finches likely underwent allopatric speciation: The isolation on different islands and the unique environmental conditions led to the development of distinct species.