Final answer:
Mate guarding is a strategy commonly associated with monogamous mating systems, where males stay close to a female to ensure paternity. This behavior is selected for in environments where suitable mates are rare and to ensure shared parental responsibility.
Step-by-step explanation:
Mate guarding is a behavior selected for in certain mating systems, particularly as a result of extra-pair copulation. Mate guarding involves males staying close to a female during the reproductive period to ensure the paternity of the offspring. This behavior is most commonly associated with monogamy, where one male and one female form a pair. The "mate-guarding hypothesis" explains this behavior as a strategy to prevent other males from mating with the female, ensuring that the mate-guarding male's genetic contribution is passed on. This is beneficial in situations where suitable mates are scarce and competitive pressures are high. In monogamous bird populations, parental care is often shared by both male and female, which may further select for monogamous mating systems and the associated mate-guarding behavior.