Which set of conditions must be met for a population to be in Hardy-Weinberg equilibrium?

• A. Mutation, small population size, migration, and natural selection.
• B. Random sampling of individuals.
• C. Frequent recombination.
• D. No mutation, random mating, large population size, no migration, and no natural selection.

Answer: (B)

Hardy-Weinberg equilibrium describes a population where allele and genotype frequencies stay constant from generation to generation when evolution isn’t acting. For this to happen, five conditions must be met: no mutations introducing new alleles, random mating, a very large population size (to prevent genetic drift), no migration, and no natural selection. When these hold, allele frequencies p and q remain constant and genotype frequencies follow p^2, 2pq, and q^2. The correct choice lists no mutation, random mating, a large population size, no migration, and no natural selection. Random sampling of individuals isn’t the same as random mating, and mutation, migration, or natural selection would disrupt equilibrium. Frequent recombination isn’t a required condition for maintaining Hardy-Weinberg frequencies across generations.