Which factor describes gene flow?

• A. Mutation
• B. Genetic drift
• C. Gene flow
• D. Natural selection

Answer: (C)

Gene flow is the movement of genetic material between populations, typically through migrating individuals or their gametes breeding in a new population. When genes move from one population to another, allele frequencies in the recipient population can change, and genetic differences between populations tend to become more similar. This is exactly what “gene flow” describes—the transfer of alleles across populations. Mutation, by contrast, introduces new alleles within a population without moving them between populations. Genetic drift is about random changes in allele frequencies due to chance, not the movement of alleles between groups. Natural selection changes allele frequencies based on fitness differences, not by moving genes from one population to another. An example: pollen blown to a nearby population or a few dispersing individuals breeding in a new area can bring new alleles into that population.