Mating systems refer to the ways in which animals pair up for reproduction. The main types include monogamy, where one male and one female mate exclusively, and polygamy, which can be further divided into polygyny (one male with multiple females) and polyandry (one female with multiple males). These systems can influence genetic diversity and social structures within species. Different species adopt various mating systems based on environmental factors and reproductive strategies. For example, in some bird species, like swans, monogamy is common, while in others, such as lions, polygyny is prevalent. These choices affect population dynamics and evolutionary processes.