a mating system should describe: (1) the interactions and resulting relationship between the mating pairs involved; and (2) the reproductive outcomes from the mating system. For instance, monogamy infers exclusive mating access and, thus, greater paternity certainty. Observed mating systems in primates include: monogamy, polyandry, polygyny and polygamy (as described below). Monogamy, or a monogamous mating system, is when one adult male and one adult female have a preferential partner for copulation. There is a long-term temporal element to this category of mating system (longer than one year or one seasonal cycle) and offspring resulting from this mating system will belong to the pair. Additionally, there is an assumption that each member in this partnership have relatively equal likelihood for successfully reproducing. Though strict monogamy is rare in nature, some primate bonded pairs demonstrate monogamous (or partially monogamous) mating systems. In some monogamous pair-bonded species there have been observations of extra-pair copulations, wherein a male or female member and a partner of the opposite sex, other than the so-called mate, have been witnessed mating. Polyandry, or a polyandrous mating system, is when one reproductive adult female mates with two or more different adult males. In this mating system, the adult males mate exclusively with the adult female. Polygyny, or a polygynous mating system, is when one adult male mates with two or more adult females. It is the most commonly type of mating system in observed in primate studies. Polygyny can occur as a result of spatial constraints where solitary males are able to defend access to nearby solitary females. Another pattern reflects a scramble competition, wherein adult males roam the landscape in search of sexually receptive females, moving on shortly after mating. Harem-polygyny occurs when a single adult male defends access to multiple females in order to gain exclusive mating access. Finally, groups of males might form coalitions in order to successfully defend mating access to females. Polygamy, or a polygamous mating system, is when both males and females mate with two or more partners. In this mating system offspring paternity might remain unknown. References Primate behavior Sociobiology