What happens to a population's allele frequencies if it is in Hardy-Weinberg equilibrium?

• A. They remain constant over generations
• B. They fluctuate randomly
• C. They always increase
• D. They always decrease

Answer: (A)

In a population that is in Hardy-Weinberg equilibrium, the allele frequencies remain constant over generations. This concept is based on a set of conditions that must be met for a population to maintain genetic stability, including a large population size, random mating, no mutations, no gene flow (immigration or emigration), and no selection. When these conditions are satisfied, the genetic makeup of the population does not change over time, which means that the frequencies of alleles stay the same across generations.

This principle provides a baseline for measuring evolutionary change and allows scientists to identify when a population may be evolving. Changes in allele frequencies over time would indicate that one or more of the Hardy-Weinberg conditions have been violated, leading to evolutionary pressures or genetic drift within the population.