Final answer:
Positive assortative mating increases the prevalence of similar genetic traits within a population, thereby potentially increasing heritability estimates for those traits by causing nonrandom mating patterns that can amplify genetic variance related to fitness-related traits.
Step-by-step explanation:
Positive assortative mating refers to when individuals preferentially choose mates with similar phenotypes to their own. This can affect heritability estimates in a population, as it can increase the probability that genetic variants responsible for those phenotypes are passed on to the offspring. Heritability refers to the fraction of population variation that can be attributed to its genetic variance. In positive assortative mating, individuals with similar desirable traits are more likely to mate, which can enhance the prevalence of those traits within the population and therefore can lead to an increase in heritability estimates for those traits. This phenomenon is particularly relevant when considering traits that are considered to be honest signals of fitness, such as those described by the good genes hypothesis and the handicap principle.