Problem:
One of your best friends, Lisa, is an ecologist who asks you to discuss her recent results with her. She studies a small population of dumbledore beetles on an isolated island in the Caribbean that she can reach only after a 5-hour boat trip from the nearest island. Dumbledore beetles are weak fliers and easy to observe and catch Lisa measured the allele frequency of a gene encoding wing color (blue or green) in this population in 2001 and again in 2011. She found that in 2001, the frequency of the green allele was 0.3 and the frequency of the blue allele was 0.7. In 2011, the frequency of the green allele had increased to 0.6 and that of the blue allele had decreased to 0.4. You're brainstorming with Lisa to figure out what may have caused this change. You go through four evolutionary mechanisms and discuss whether each is likely or unlikely to account for the change in allele frequencies: mutation, gene flow (migration), genetic drift, and natural selection.
Required:
Question 1: Which one(s) is/are likely to account for the change? Explain your answer.
Question 2: Which one(s) is/are unlikely to have played a role? Explain your answer.