Impacts of Intergroup Interactions on Intragroup Behavioral Changes in Javan Gibbons (Hylobates moloch)

Yi, Yoonjung; Fichtel, Claudia; Kim, Erick; Choe, Jae Chun

doi:10.1007/s10764-019-00116-8

Cited by 18 publications

(10 citation statements)

References 56 publications

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“…Our results, demonstrating that intergroup competition precipitates positive in-group dynamics, accord with previous findings in human (Bernhard et al 2006;Gneezy and Fessler 2012;Puurtinen and Mappes 2009;Yamagishi and Mifune 2009), and nonhuman animals (Bruintjes et al 2015;Majolo et al 2016;Mirville et al in press;Radford 2008;Samuni et al 2017). Conversely, there is substantial lack of evidence for the effect of intergroup competition on positive in-group dynamics across primate species (Cheney 1992;Chism and Rogers 2004;Grueter 2013;Polizzi di Sorrentino et al 2012;Yi et al 2019). Evident variability in how intergroup competition and in-group cohesion are linked across studies and species provides an important basis to ask what potential selective pressures explain interstudy or interspecies discrepancies.…”

Section: Discussionsupporting

confidence: 91%

“…Similar to humans, intergroup competition occurrence was associated with enhanced in-group affiliation and/or cohesion in several nonhuman primate and nonprimate species (Bruintjes et al 2015;Majolo et al 2016;Mirville et al in press;Preis et al 2019;Radford 2008;Samuni et al 2017). However, other studies found no such relation (Cheney 1992;Chism and Rogers 2004;Grueter 2013;Polizzi di Sorrentino et al 2012;Yi et al 2019). This lack of consensus emphasizes that such a link likely depends on several factors such as the social system, the intensity of intergroup competition, and the potential cost-to-benefit ratios from group-level attacks on rivals.…”

Section: Introductionmentioning

confidence: 98%

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Intergroup Competition Enhances Chimpanzee (Pan troglodytes verus) In-group Cohesion

et al. 2019

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In-group cohesion is an essential component of successful intergroup competition in both human and nonhuman animals, likely facilitating group members access to potential benefits. However, when benefits are equally shared among group members, group defense becomes a collective action problem, which might subvert cohesive participation during intergroup competition. There is a lack of consensus across studies and species with regard to the link between in-group cohesion and intergroup competition, likely as a result of species differences in managing the collective action problem. Here, we examine this link in a species with a striking example of collective action during intergroup competition, chimpanzees (Pan troglodytes verus). Using two years of focal-follow data on males and females in two groups at the Taï Forest, Côte d'Ivoire, we investigated the immediate and long-term effects of intergroup competition (border patrols and intergroup encounters) on measures of in-group cohesion, namely modularity, party size, and intergroup aggression. We found that groups' association patterns were less modular (more cohesive) in months in which they engaged in more border patrols and intergroup encounters. We found that current and greater prior engagement in intergroup competition predicted larger party sizes. Furthermore, current, but not prior engagement in intergroup competition, predicted reduced intragroup aggression by males but not by females. Increased in-group cohesion in chimpanzees likely reduces potential costs of intergroup competition engagement, by facilitating joint participation in current and future intergroup conflicts, overcoming the collective action problem.

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Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 98%

Intergroup Competition Enhances Chimpanzee (Pan troglodytes verus) In-group Cohesion

et al. 2019

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“…If so, the predicted greater likelihood that dominant animals aggressively participate in IGEs might be masked by the alternative strategies employed by subordinates. Interactions between groups, involving close-distance aggression, long-distance calls, and intergroup affiliation or avoidance, affect intragroup social dynamics over the short and longterm (Majolo et al 2016;Mirville et al in press;Radford et al 2016;Samuni et al 2019;Yi 2019). Thus, individual decisions during IGEs can be driven by the complex interplay of the social and ecological benefits that each animal gains/loses during social interactions with its group members and with the opposing group, which will make it hard to detect generalizable commonalities across a wide range of species in meta-analyses such as ours.…”

Section: Discussionmentioning

confidence: 99%

Effect of Group Size and Individual Characteristics on Intergroup Encounters in Primates

et al. 2020

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Intergroup encounters are common in nonhuman primates and can vary from affiliative to aggressive. We extracted data from the literature to test five different hypotheses: 1) where there are group size differences between opposing groups, whether the larger group is more likely to win an intergroup encounter than the smaller group; 2) whether the likelihood of a group engaging in aggressive intergroup encounters increases with group size; and 3-5) whether dominant, older individuals, and/or males are more likely to participate aggressively in intergroup encounters than subordinate, younger individuals and/or females. Our data set comprised 52 studies on 31 primate species (3 lemur species, 5 New World monkeys, 19 Old World monkeys, and 4 apes). We found that the larger group is more likely to win an encounter against a smaller group than vice versa. We found no significant relationship between group size and propensity to be aggressive during intergroup encounters. We found weak/no support for the effect of age, dominance rank, and sex on the frequency of aggression displayed toward outgroup individuals during intergroup encounters. Species-and population-specific differences in inter-and intragroup competition and in the degree of the unequal distribution of resources across group members may explain why age, dominance rank, and sex are not strong predictors of aggression during intergroup encounters.

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“…Reduced grooming after exposure to intergroup threats may therefore reflect increased stress, vigilance, or other defensive activities, after an initial short‐lived increase for social bonding or stress relief. In gibbons, reduced grooming between pairs after intergroup encounters is suggested to be a byproduct of increased foraging, after a reduction in foraging time during encounters (Yi et al, 2020 ). In general, behaviors such as grooming (and, potentially, aggression) that may appear similar in different species may function differently and be expressed in different contexts, depending on ecology, social structure, and sensory abilities.…”

Section: Discussionmentioning

confidence: 99%

The dynamics of social cohesion in response to simulated intergroup conflict in banded mongooses

Preston

Thompson

Kyabulima³

et al. 2021

Ecology and Evolution

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Impacts of Intergroup Interactions on Intragroup Behavioral Changes in Javan Gibbons (Hylobates moloch)

Cited by 18 publications

References 56 publications

Intergroup Competition Enhances Chimpanzee (Pan troglodytes verus) In-group Cohesion

Intergroup Competition Enhances Chimpanzee (Pan troglodytes verus) In-group Cohesion

Effect of Group Size and Individual Characteristics on Intergroup Encounters in Primates

The dynamics of social cohesion in response to simulated intergroup conflict in banded mongooses

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