A
mating system is a way in which a group is structured in relation to sexual behaviour. The precise meaning depends upon the context. With respect to
animals, the term describes which males and females
mate, under which circumstances; recognised systems include
monogamy,
polygamy (which includes
polygyny,
polyandry, and
polygynandry), and
promiscuity, all of which lead to different
mate choice outcomes and thus these systems affect how
sexual selection works in the species which practice them. In plants, the term refers to the degree and circumstances of
outcrossing. In human
sociobiology, the terms have been extended to encompass the formation of relationships such as
marriage.