Assortative mating

Assortative mating is nonrandom pairing in which individuals choose mates with similar or dissimilar traits more often than expected by chance. Positive assortment favors similarity; negative assortment favors difference.

Positive assortative mating: Nonrandom mating in which individuals preferentially pair with others resembling them in one or more traits. It is the similarity-favoring form of assortative mating.
Heterozygosity: The condition of carrying different alleles at a genetic locus, measured across individuals or populations. Positive assortment can reduce heterozygosity at loci associated with preferred traits.
Mate choice: Behavioral preferences and decisions that influence which individuals become reproductive partners. Observed mate preferences are one route through which assortative mating arises.
Disassortative mating: Mate choice that favors partners differing at specified traits or genetic markers. It is the negative-assortment pattern, contrasted with similarity-favoring pairing.
Negative assortative mating: Nonrandom mating in which individuals preferentially pair with others differing in one or more traits. It is the difference-favoring form of assortative mating.
Genetic variance: The portion of variation among individuals attributable to differences in their genotypes. Assortative pairing changes how genetic differences are distributed across a population.
Population genetics: The study of genetic variation and its change within and between populations. Assortative mating is modeled to predict population-level genetic patterns.
Random mating: A mating pattern in which partner pairing is independent of the trait or genotype under study. It provides the baseline against which assortative mating is defined.
Inbreeding: Reproduction between genetically related individuals, increasing the chance that offspring inherit identical alleles from both parents. Preference for similar traits can increase related mating, though the two are not equivalent.
Reproductive isolation: Barriers that reduce or prevent gene exchange between populations or groups. Assortative mating by traits can reduce interbreeding and contribute to isolation.

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