Jealous females? Female competition and reproductive suppression in a wild promiscuous primate

Female–female competition over paternal care has rarely been investigated in promiscuous mammals, where discreet forms of male care have recently been reported despite low paternity certainty. We investigated female competition over paternal care in a wild promiscuous primate, the chacma baboon ( Papio ursinus ), where pregnant and lactating females establish strong social bonds (friendships) with males that provide care to their offspring. We tested whether pregnant and lactating females interfere with the sexual activity of their male friend to prevent new conceptions that might lead to the subsequent dilution of his paternal care. We found that pregnant and lactating females were more aggressive towards oestrous females when they had recently conceived themselves, and when the oestrous female was mate-guarded by, and showed greater sexual activity with, their male friend. This aggression also reduced the likelihood of conception of the targeted female. These findings indicate that females can aggressively prevent further conceptions with their offspring's carer through reproductive suppression. Competition over access to paternal care may play an important and underestimated role in shaping female social relationships and reproductive strategies in promiscuous mammalian societies.

Socio-behavioral convergence in female affiliative behaviors in Pan and Ateles

Pan and Ateles converge in many aspects of their social organization. Both are characterized by a high degree of fission-fusion dynamics, in which species exhibit high variation in party size, composition, and spatial cohesion. Within this framework, chimpanzees (Pan troglodytes) and spider monkeys (Ateles sp.) exhibit the most similarity in subgrouping patterns and social relationships. Specifically, significant overlap is found in the context of female social relationships and patterns of male-female aggression. Here, we examine how affiliative behaviors mediate female social relationships in captive spider monkeys, chimpanzees, and bonobos. Focal data were collected from five female Ateles geoffroyi at Brookfield Zoo (mean age=13.2, range: 7-21), five female bonobos at Columbus Zoo (mean age=22.0, range: 7-31), and five chimpanzees at North Carolina Zoo (mean age=20.4, range: 15-43). Female dyads did not differ in their rates of total or directional grooming, but spider monkeys engaged in significantly less mutual grooming (Kruskal-Wallis H= 8.917, N=30, p=0.012). All three species exhibited grooming reciprocity. There were no significant differences in the overall use of tension-reduction behaviors. However, there were significant differences in the types of tension-reduction behaviors, with spider monkeys using embraces (H=14.306, p=0.001), bonobos using socio-sexual behaviors (H=14.269, p=0.001), and chimpanzees using kisses (H=11.50, p=0.003). Furthermore, bonobos used tension-reduction behaviors significantly more often in feeding contexts (ANOVA F=14.357, N=15, p=0.001). We suggest that each species use tension-reduction behaviors that are species-typical, but serve as functional equivalents. However, bonobos may experience increased tension in feeding contexts, which suggests differing social and ecological pressures may necessitate an increase in tension-reduction behaviors.

Socio-behavioral convergence in female affiliative behaviors in Pan and Ateles

Pan and Ateles converge in many aspects of their social organization. Both are characterized by a high degree of fission-fusion dynamics, in which species exhibit high variation in party size, composition, and spatial cohesion. Within this framework, chimpanzees (Pan troglodytes) and spider monkeys (Ateles sp.) exhibit the most similarity in subgrouping patterns and social relationships. Specifically, significant overlap is found in the context of female social relationships and patterns of male-female aggression. Here, we examine how affiliative behaviors mediate female social relationships in captive spider monkeys, chimpanzees, and bonobos. Focal data were collected from five female Ateles geoffroyi at Brookfield Zoo (mean age=13.2, range: 7-21), five female bonobos at Columbus Zoo (mean age=22.0, range: 7-31), and five chimpanzees at North Carolina Zoo (mean age=20.4, range: 15-43). Female dyads did not differ in their rates of total or directional grooming, but spider monkeys engaged in significantly less mutual grooming (Kruskal-Wallis H= 8.917, N=30, p=0.012). All three species exhibited grooming reciprocity. There were no significant differences in the overall use of tension-reduction behaviors. However, there were significant differences in the types of tension-reduction behaviors, with spider monkeys using embraces (H=14.306, p=0.001), bonobos using socio-sexual behaviors (H=14.269, p=0.001), and chimpanzees using kisses (H=11.50, p=0.003). Furthermore, bonobos used tension-reduction behaviors significantly more often in feeding contexts (ANOVA F=14.357, N=15, p=0.001). We suggest that each species use tension-reduction behaviors that are species-typical, but serve as functional equivalents. However, bonobos may experience increased tension in feeding contexts, which suggests differing social and ecological pressures may necessitate an increase in tension-reduction behaviors.

Socioecology of wild bearded capuchin monkeys (Sapajus libidinosus): an analysis of social relationships among female primates that use tools in feeding

Socioecology considers that the features of food sources affect female social relationships in group-living species. Among primates, the tests of socioecological models are largely focused on Old World species and do not evaluate if the use of feeding tools affects the competitive regime over food and females’ relations in wild populations. We studied female social relationships among a wild population of bearded capuchins monkeys (Sapajus libidinosus) that use percussive tools (stones) to crack encased foods, in a semi-arid habitat in Brazil. Females fed mainly on clumped, high quality resources, indicating that the habitat provides a high quality diet year-round. Females experienced contest competition within and between-groups. As predicted by socioecological models, females’ social relationships were characterized by philopatry, linear dominance hierarchies, coalitions, and tolerance in feeding bouts. Females spent a small proportion of their feeding time using tools. Nevertheless, tool sites generated high rates of contest competition and lower indices of tolerance among females. Although the social structure of our study population did not differ significantly from the pattern observed in wild populations of Sapajus that do not use tools, tool use increased within-group contest competition and apparently contributed to the linearity of the dominance hierarchies established among females. We predict that when tool use results in usurpable food resources, it will increase contest competition within group-living species.