Females drive primate social evolution

Stockholm University, Tukholma, Stockholm, Sweden
Proceedings of the Royal Society B: Biological Sciences (Impact Factor: 5.05). 03/2004; 271 Suppl 3(Suppl_3):S101-3. DOI: 10.1098/rsbl.2003.0114
Source: PubMed


Within and across species of primates, the number of males in primate groups is correlated with the number of females. This correlation may arise owing to ecological forces operating on females, with subsequent competition among males for access to groups of females. The temporal relationship between changes in male and female group membership remains unexplored in primates and other mammalian groups. We used a phylogenetic comparative method for detecting evolutionary lag to test whether evolutionary change in the number of males lags behind change in the number of females. We found that change in male membership in primate groups is positively correlated with divergence time in pairwise comparisons. This result is consistent with male numbers adjusting to female group size and highlights the importance of focusing on females when studying primate social evolution.

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    • "These fissioning events create unique opportunities for matrilocal females to disperse [Dittus, 1988; Hamilton & Bulger, 1993; Melnick & Kidd, 1983; Ménard & Vallet, 1993; Sussman, 1992; Widdig et al., 2006, but see Van Horn et al., 2007], providing an escape from high levels of intragroup competition for food resources and the associated difficulties in maintaining social cohesion [Chapman & Chapman, 2000; Isbell, 1991; Izar, 2004; Janson & van Schaik, 1988; Majolo et al., 2008; Snaith & Chapman, 2007]. While females fission in response to the high costs of feeding competition as group sizes increase [Altmann & Alberts, 2003; Borries et al., 2008; Fedigan & Jack, 2011; Majolo et al., 2008; Ryan et al., 2008; Van Belle & Estrada, 2008], males follow the females, distributing themselves among female groups with the most favorable sex ratios [Altmann, 1990, 2000; Cords, 2000; Lindenfors et al., 2004; Nunn, 1999]. Although temporary group fission (fission–fusion ) is widespread in patrilocal species [e.g., Aureli et al., 2008; Symington, 1990], permanent group fission has only been reported in chimpanzees [Pan troglodytes: Goodall, 1983, 1986], northern muriquis [Brachyteles hypoxanthus: Strier et al., 1993, 2006], and more recently, in spider monkeys [Ateles geoffroyi: Aureli et al., 2013]. "
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    ABSTRACT: Although well documented in matrilocal primate species, group fission is still a poorly known phenomenon among patrilocal primates. In this paper we describe in detail a group fission event in the population of northern muriquis at the Reserva Particular do Patrimônio Natural-Feliciano Miguel Abdala in Caratinga, Minas Gerais, Brazil, using Social Network Analyses (SNA). Data on association patterns were collected during systematic observations from May 2002 to September 2005, and analyzed for dry (from May to October) and rainy seasons (from November to April). The fission process started with subgroup formation in the rainy season 2002-2003, and was completed by the dry season of 2003. By the dry season 2003, the parent group (Jaó) had fissioned to form a second mixed-sex group (Nadir) while a subgroup of males (MU) moved between the parent group and the newly established group. Before the Jaó group fission started (dry season 2002) and during its initial phases (rainy season 2002-2003), females that ultimately composed the daughter group (Nadir) were the most peripheral in the association network. In the rainy season 2002-2003, the median monthly (N = 6) operational sex ratio (OSR) of Jaó group was 2.81. However, once Jaó females initiated the fissioning process to establish the Nadir group, the OSR was more favorable to males in the Nadir group than in the Jaó group. Our results suggest that males followed the females to escape an unfavorable OSR in their natal group. Am. J. Primatolxd. © 2013 Wiley Periodicals, Inc.
    American Journal of Primatology 06/2014; 76(6):529-538. DOI:10.1002/ajp.22244 · 2.44 Impact Factor
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    • "In nonhuman primates, females typically drive the evolution of the social system, highlighting the importance of focusing on females when studying primate social evolution [Clutton-Brock & Lukas, 2012; Lindenfors et al., 2004]. Female primate social structures vary greatly between species, ranging from females forming loose and changing associations, to females establishing stable bonds with a subset of partners [Wrangham, 1980]. "
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    ABSTRACT: In primates, females typically drive the evolution of the social system and present a wide diversity of social structures. To understand this diversity, it is necessary to document the consistency and/or flexibility of female social structures across and within species, contexts, and environments. Macaques (Macaca sp.) are an ideal taxon for such comparative study, showing both consistency and variation in their social relations. Their social styles, constituting robust sets of social traits, can be classified in four grades, from despotic to tolerant. However, tolerant species are still understudied, especially in the wild. To foster our understanding of tolerant societies and to assess the validity of the concept of social style, we studied female crested macaques, Macaca nigra, under entirely natural conditions. We assessed their degree of social tolerance by analyzing the frequency, intensity, and distribution of agonistic and affiliative behaviors, their dominance gradient, their bared-teeth display, and their level of conciliatory tendency. We also analyzed previously undocumented behavioral patterns in grade 4 macaques: reaction upon approach and distribution of affiliative behavior across partners. We compared the observed patterns to data from other populations of grade 4 macaques and from species of other grades. Overall, female crested macaques expressed a tolerant social style, with low intensity, frequently bidirectional, and reconciled conflicts. Dominance asymmetry was moderate, associated with an affiliative bared-teeth display. Females greatly tolerated one another in close proximity. The observed patterns matched the profile of other tolerant macaques and were outside the range of patterns of more despotic species. This study is the first comprehensive analysis of females’ social behavior in a tolerant macaque species under natural conditions and as such, contributes to a better understanding of macaque societies. It also highlights the relevance of the social style concept in the assessment of the degree of tolerance/despotism in social systems.
    American Journal of Primatology 04/2013; 75:361-375. DOI:10.1002/ajp.22114 · 2.44 Impact Factor
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    • "In accord with previous comparative studies [10], [16], [61], the best predictor of the number of males in a primate group was the spatial patchiness of females measured as the number of females in that group. Indeed, a previous study found that evolutionary changes in the number of males in a group lags behind the change in the number of females [61]. "
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    ABSTRACT: The spatiotemporal distribution of females is thought to drive variation in mating systems, and hence plays a central role in understanding animal behavior, ecology and evolution. Previous research has focused on investigating the links between female spatiotemporal distribution and the number of males in haplorhine primates. However, important questions remain concerning the importance of spatial cohesion, the generality of the pattern across haplorhine and strepsirrhine primates, and the consistency of previous findings given phylogenetic uncertainty. To address these issues, we examined how the spatiotemporal distribution of females influences the number of males in primate groups using an expanded comparative dataset and recent advances in bayesian phylogenetic and statistical methods. Specifically, we investigated the effect of female distributional factors (female number, spatial cohesion, estrous synchrony, breeding season duration and breeding seasonality) on the number of males in primate groups. Using bayesian approaches to control for uncertainty in phylogeny and the model of trait evolution, we found that the number of females exerted a strong influence on the number of males in primate groups. In a multiple regression model that controlled for female number, we found support for temporal effects, particularly involving female estrous synchrony: the number of males increases when females are more synchronously receptive. Similarly, the number of males increases in species with shorter birth seasons, suggesting that greater breeding seasonality makes defense of females more difficult for male primates. When comparing primate suborders, we found only weak evidence for differences in traits between haplorhines and strepsirrhines, and including suborder in the statistical models did not affect our conclusions or give compelling evidence for different effects in haplorhines and strepsirrhines. Collectively, these results demonstrate that male monopolization is driven primarily by the number of females in groups, and secondarily by synchrony of female reproduction within groups.
    PLoS ONE 05/2011; 6(5):e19853. DOI:10.1371/journal.pone.0019853 · 3.23 Impact Factor
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