Final answer:
Assortative and disassortative mating both change only the expected Hardy-Weinberg genotype frequencies, not allele frequencies, in a population, and are types of nonrandom mating.
Step-by-step explanation:
Assortative and disassortative mating are similar in that both change only the expected Hardy-Weinberg genotype frequencies in a population. These types of nonrandom mating patterns do not directly change allele frequencies but instead affect which genotypes are more likely to come together. Assortative mating occurs when individuals tend to mate with those who are phenotypically similar to themselves, while disassortative mating happens when individuals preferentially mate with those who are phenotypically different. Both strategies alter the genetic structure without altering the allele frequency, hence, they disrupt the Hardy-Weinberg equilibrium by affecting the frequencies of genotypes.