Final answer:
Polygyny is a mating system where one male mates with multiple females, commonly found in species with territorial mating practices or where males offer desirable resources to females. It can also occur in human societies for economic and social benefits. Three common polygynous structures are resource-based polygyny, harem mating, and lek systems in different species.
Step-by-step explanation:
There are several reasons for polygyny, which refers to a mating system where one male mates with multiple females. This system is often observed in species where males compete for territories that have the best resources, which in turn attracts females. Common forms of polygyny include resource-based polygyny, harem mating structures, and lek systems.
In resource-based polygyny, the competition is for territories rich in resources that female partners find attractive. An example of this can be seen in the yellow-rumped honeyguide, where males defend beehives with wax that is a valuable resource for females. In harem mating structures, an alpha male dominates mating within a group by controlling a territory with resources, a behavior observed in elephant seals. Lastly, a lek system involves a communal courting area where males perform displays for females who then choose their mates, which is common in bird species like sage grouse and prairie chicken.
Polygyny is also practiced in human societies and can be economically beneficial as it maximizes the labor force, shared resources, and creates extensive kinship networks. However, it can also lead to social and economic complexities within the family and the broader community.