A comparative study of conflict resolution in macaques: insights into the nature of trait covariation

Conflict resolution is an essential component of primate sociality that has been studied extensively within primate social groups, but few studies have examined how conflict resolution behaviours covary at evolutionary scales. We assembled a standardized data set on social interactions of sexually mature females to analyse patterns of conflict resolution in 15 groups of nine macaque species. Between-group comparisons revealed no significant difference in nonkin reconciliation levels between groups of the same species, whereas substantial interspecific differences were found. We tested for associations between four behavioural traits involving reconciliation and dominance asymmetry that play a central role in primate social systems. Regression analyses using group values indicated that these traits (conciliatory tendencies, proportions of explicit reconciliatory contacts, kin bias and levels of counteraggression) exist as an integrated suite of characters. We found strong phylogenetic signal in most traits, which further indicates that they evolved during the adaptive radiation of macaques. Using the method of independent contrasts, relationships between conciliatory tendencies and proportions of explicit reconciliatory contacts and between kin bias and levels of counteraggression remained consistent after controlling for phylogeny. This reveals that evolutionary change in one trait leads to correlated changes in other traits. Collectively, these results show how comparative studies of detailed behavioural interactions can be used to elucidate primate socioecology. (c) 2007 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.