Nested Male Reproductive Strategies in a Tolerant Multilevel Primate Society

Abstract

Male reproductive success varies within populations. Models explaining reproductive skew emphasise dominance, yet the determinants of male reproductive success in egalitarian societies remain poorly understood. Using nine years of behavioural and genetic data from five parties, we investigated male reproductive monopolisation in wild Guinea baboons (*Papio papio*), an egalitarian multilevel society with one-male "units" nested within "parties" and low male-male contest competition. Genetic analyses showed 93% of the 69 infants were sired by the female's "unit male", with extra-unit paternities consistent with limited control models. Reproduction was distributed among multiple unit males, resulting in low reproductive skew at the party level, with top males siring 23-40% of offspring, well below levels in despotic species. Female takeovers were rare, suggesting male restraint. Among prime-aged males, the number of unit females was only weakly positively associated with dominance ratings. Prime-age predicted reproductive success better than dominance. Non-prime-aged males had fewer females across dominance ratings. In conclusion, male Guinea baboons' reproductive potential is shaped less by dominance than by age and stable associations with females, who play an active role in inter-sexual relationships. These results emphasise the need to move beyond frameworks focused solely on dominance-based mechanisms and to consider species-specific social organisation.