Assortative mating

Assortative mating (also referred to as positive assortative mating or homogamy) is a mating pattern and a form of sexual selection in which individuals with similar phenotypes or genotypesmate with one another more frequently than would be expected under a random mating pattern.

A majority of the phenotypes that are subject to assortative mating are body size, visual signals (e.g. color, pattern), and secondary sexual traits such as crest size.

The opposite of assortative is disassortative mating, also referred to "negative assortative mating", in which case its opposite is termed "positive assortative mating".