Which factor would disrupt the Hardy-Weinberg law of equilibrium, potentially leading to evolutionary change?

• A. Random mating
• B. Environmental stability
• C. Non-random mating
• D. Large population size

Answer: (C)

Non-random mating is a factor that disrupts the Hardy-Weinberg law of equilibrium and can lead to evolutionary change. The Hardy-Weinberg principle establishes conditions under which a population's allele frequencies will remain constant over generations, meaning that the population is in genetic equilibrium. One of these conditions is that individuals in the population must mate randomly with respect to their genotypes.

When non-random mating occurs, certain genotypes may have a higher chance of reproducing than others. This can lead to an increase in the frequency of certain alleles over time while reducing the genetic diversity within the population. For example, if individuals preferentially mate with those who are similar or dissimilar to themselves (assortative or disassortative mating), this selective pairing can cause deviations from the expected ratios of genotypes, thus influencing the evolutionary trajectory of the population.

In contrast, random mating helps maintain the genetic makeup of the population across generations because it ensures that all individuals have an equal opportunity to contribute to the next generation's genetic pool. Other factors like environmental stability and large population size do not disrupt the conditions outlined in the Hardy-Weinberg principle, as they do not inherently lead to changes in allele frequencies within a population.