% pubman genre = article @article{item_3148621, title = {{Intergroup competition enhances chimpanzee (Pan troglodytes verus) in-group cohesion}}, author = {Samuni, Liran and Mielke, Alexander and Preis, Anna and Crockford, Catherine ǂ and Wittig, Roman M.}, language = {eng}, issn = {0164-0291}, doi = {10.1007/s10764-019-00112-y}, publisher = {Springer}, address = {New York}, year = {2020}, date = {2020}, abstract = {{In-group cohesion is an essential component of successful intergroup competition in{\textless}br{\textgreater}both human and nonhuman animals, likely facilitating group members access to{\textless}br{\textgreater}potential benefits. However, when benefits are equally shared among group members,{\textless}br{\textgreater}group defense becomes a collective action problem, which might subvert cohesive{\textless}br{\textgreater}participation during intergroup competition. There is a lack of consensus across studies{\textless}br{\textgreater}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{\textless}br{\textgreater}problem. Here, we examine this link in a species with a striking example of collective{\textless}br{\textgreater}action during intergroup competition, chimpanzees (Pan troglodytes verus). Using two{\textless}br{\textgreater}years of focal-follow data on males and females in two groups at the Ta{\"\i} Forest, C{\^o}te{\textless}br{\textgreater}d{\textquoteright}Ivoire, we investigated the immediate and long-term effects of intergroup competition{\textless}br{\textgreater}(border patrols and intergroup encounters) on measures of in-group cohesion, namely{\textless}br{\textgreater}modularity, party size, and intergroup aggression. We found that groups{\textquoteright} association{\textless}br{\textgreater}patterns were less modular (more cohesive) in months in which they engaged in more{\textless}br{\textgreater}border patrols and intergroup encounters. We found that current and greater prior{\textless}br{\textgreater}engagement in intergroup competition predicted larger party sizes. Furthermore, current, but not prior engagement in intergroup competition, predicted reduced intragroup{\textless}br{\textgreater}aggression by males but not by females. Increased in-group cohesion in chimpanzees{\textless}br{\textgreater}likely reduces potential costs of intergroup competition engagement, by facilitating{\textless}br{\textgreater}joint participation in current and future intergroup conflicts, overcoming the collective{\textless}br{\textgreater}action problem.}}, journal = {{International Journal of Primatology}}, volume = {41}, pages = {342--362}, }