What is the term for the natural mutations which cause animal strains to undergo change in genotype?

• A. Recombinance
• B. Genetic drift
• C. Mutational shift
• D. Natural crossover

Answer: (B)

Genetic drift describes random fluctuations in allele frequencies from one generation to the next, driven by chance. In small animal strains, these random sampling effects can cause some alleles to become more common or disappear entirely over generations, leading to changes in genotype makeup even without any selection pressure. This contrasts with recombination or crossover, which shuffle existing alleles within a generation to create new combinations but don’t by themselves drive random shifts in allele frequencies across generations. Mutations introduce new genetic variation, but the term drift specifically captures the population-level, stochastic changes in genotype frequencies over time.