Final answer:
In rats, the commonly used mating systems are monogamy, where one male pairs with one female, and polygyny, where one male mates with multiple females. Monogamy may be based on various hypotheses such as mate-guarding, male-assistance, or female-enforcement, while polygyny includes several types such as resource-based, harem, and lek systems.
Step-by-step explanation:
The two mating systems commonly used in rats are monogamy and polygyny. In a monogamous system, one male and one female are paired for at least one breeding season, which may last longer in some species. This system may be based on the mate-guarding hypothesis, male-assistance hypothesis, or female-enforcement hypothesis. Polygyny refers to one male mating with multiple females, and it can take different forms such as resource-based polygyny, harem mating, and leks. Polyandrous systems, where one female mates with many males, are rarer and not commonly observed in rats.