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

Explanation:

1. Recall the definitions of each mechanism:

• Genetic drift: Random changes in gene pool due to chance events (like disasters reducing population size, bottleneck effect).
• Gene flow: Transfer of genes between populations (migration, etc.).
• Gene mutation: Permanent change in DNA sequence (not directly caused by a disaster reducing population).
• Genetic variation: Overall diversity in a gene pool (not a mechanism causing change here).

1. The oil spill is a disaster that likely killed many organisms, reducing the population size drastically. This is a bottleneck effect, a type of genetic drift. The other mechanisms don't fit: gene flow requires movement between populations, gene mutation is a DNA change (not caused by population reduction), and genetic variation is the result, not the mechanism here.

Answer:

genetic drift