The Utility of Reproductive Skew Models in the Study of Male Primates, a Critical Evaluation

The number of adult males in a group is one of the most variable aspects of primate social organization. The causes for this variation have constituted a longstanding focus in primatological research.(1) As a male's reproductive success is mainly limited by access to females,(2) competition among males should result in the exclusion of rivals from groups of females.(4,5) However, a great number of primate species live in groups with several adult males. To explain the causes and consequences of this shared male group membership, primatologists have begun to examine the phenomenon within the framework of reproductive skew theory. This body of game theoretical models was developed to examine variation in reproductive skew within and across populations and species and to explain the preconditions for stable associations, as well as how reproduction should be distributed therein.(6-9) Here we summarize the main aspects of this theory, review its application to studies of male reproductive strategies, and identify pitfalls associated with using this approach.