What are 4 ways to change gene frequency?

• A. Random drift
• B. Mutation
• C. Migration
• D. Random drift, Mutation, Migration, and Selection

Answer: (D)

Gene frequencies in a population change through four main evolutionary forces: random drift, mutation, migration, and selection. Random drift causes allele frequencies to fluctuate by chance, especially in small populations, and can lead to alleles becoming fixed or lost. Mutation introduces new alleles or alters existing ones, providing new genetic variation. Migration, or gene flow, moves alleles between populations, changing frequencies in both donor and recipient populations. Selection changes frequencies by differential reproductive success, increasing the frequency of advantageous alleles over generations. Because the question asks for four ways, listing all four mechanisms gives the complete answer. The other options only mention one or a subset of these forces, so they don’t capture all the ways gene frequencies can change.