What does Hardy-Weinberg Equilibrium state?

• A. Allele and genotype frequencies will change each generation in the absence of evolutionary influences.
• B. Allele frequencies remain constant but genotype frequencies vary.
• C. Allele and genotype frequencies remain constant from generation to generation in the absence of evolutionary influences.
• D. The equilibrium only applies to asexual populations.

Answer: (C)

Hardy-Weinberg equilibrium describes a situation in which nothing that can cause evolution is acting on a population. When conditions are met—no mutation, no migration, no natural selection, a very large population, and random mating—the frequencies of the two alleles (p and q) stay the same from one generation to the next, and the genotype frequencies settle into p^2, 2pq, and q^2. So the statement that both allele and genotype frequencies remain constant across generations in the absence of evolutionary influences is the best description. The other ideas misstate how genotype frequencies relate to allele frequencies or what kinds of populations the principle applies to.