Assortative Mating - Animals

Animals

It is believed that the American Robin practices assortative mating on plumage color, a melanin based trait. However, in female American Robins, dark plumage indicates reproductive performance, while dark plumage in males indicates health and decreased parental investment. Nevertheless, positive assortment based on plumage color may explain the American Robin’s unique mating pattern of remaining together throughout the breeding season but never reuniting in subsequent breeding seasons. Because assortative mating based on plumage color adequately predicts reproductive success, there are higher levels of fidelity and less need for extra pair relations.

Positive assortative mating is believed to be the cause of the speciation of a daughter species from the parent species of coral-dwelling goby fish. The species live in a small area of rare coral in the ocean around Bootless Bay in southern Papua New Guinea which the parent species shun. The daughter species has become reproductively isolated from the parent species even though the parent species surrounds the daughter species so there is no geographic isolation. The speciation in the early stages would depend on assortative mating in which the evolving goby fishes would prefer to mate with other fish that preferred to spawn in the same area of rare coral.