Which factor would cause allele frequencies to change in a population, violating Hardy-Weinberg equilibrium?

Which factor would cause allele frequencies to change in a population, violating Hardy-Weinberg equilibrium?

• A. Random mating
• B. No mutation
• C. Large population size
• D. Natural selection

Answer: (D)

Hardy-Weinberg equilibrium describes a population in which allele frequencies stay constant from one generation to the next when no evolutionary forces are acting. Natural selection is the factor that would change those frequencies because it creates differences in reproductive success among individuals with different alleles. If an allele confers higher fitness, individuals carrying it contribute more offspring, increasing that allele’s frequency over generations. The other factors align with the conditions that keep Hardy-Weinberg expectations: random mating tends to maintain the proportion of genotypes corresponding to the current allele frequencies, no mutation means no new alleles are introduced, and a very large population minimizes random genetic drift. While mutation, drift, and migration can alter frequencies over time, natural selection is the force that directly shifts allele frequencies in the population, violating the equilibrium.

Hardy-Weinberg equilibrium describes a population in which allele frequencies stay constant from one generation to the next when no evolutionary forces are acting. Natural selection is the factor that would change those frequencies because it creates differences in reproductive success among individuals with different alleles. If an allele confers higher fitness, individuals carrying it contribute more offspring, increasing that allele’s frequency over generations.

The other factors align with the conditions that keep Hardy-Weinberg expectations: random mating tends to maintain the proportion of genotypes corresponding to the current allele frequencies, no mutation means no new alleles are introduced, and a very large population minimizes random genetic drift. While mutation, drift, and migration can alter frequencies over time, natural selection is the force that directly shifts allele frequencies in the population, violating the equilibrium.