Question

Changes in the gene pool can occur due to various mechanisms. In 1989, a large oil spill occurred in Prince William Sound, Alaska, when the Exxon Valdez oil tanker ran aground. Approximately 11 million gallons of oil were spilled and spread 1,300 miles along the Alaskan coastline. The damage from the oil spill affected thousands of animals in the area, including killer whales, harbor seals, sea otters, fish, and sea birds. Which mechanism most likely affected the gene pools of the organism populations in the areas around the oil spill?
genetic drift
gene flow
gene mutation
genetic variation

Answer 1

Genetic drift — the spill caused large, random reductions in population sizes (a bottleneck), so allele frequencies would change by chance rather than by selection or migration.