Assortative mating

Assortative mating is a mating pattern and a form of sexual selection in which individuals with similar genotypes and/or phenotypes mate with one another more frequently than would be expected under a random mating pattern. Examples of similar phenotypes include, but are not limited to, body size, skin coloration/pigmentation, and age. Assortative mating, also referred to as positive assortative mating or homogamy, may increase genetic relatedness within the family. Assortative mating can be contrasted with disassortative mating (also known as negative assortative mating or heterogamy) in which individuals with dissimilar genotypes and/or phenotypes mate with one another more frequently than would be expected under random mating. Disassortative mating reduces the genetic similarities within the family. Positive assortative mating occurs more frequently than negative assortative mating. In both cases, due to the nonrandom mating pattern, there is a deviation from the Hardy–Weinberg principle.