Behavioral syndromes are associated with social plasticity and competence in a wild primate

Abstract The ability to optimize social behavior to varying socioecological circumstances has been termed “social competence” and relies on behavioral plasticity. Behavioral syndromes, i.e. consistent individual differences in intraindividual correlations among behavioral traits, appear to be a constraint on social competence, yet studies exploring this have largely been limited to experimental laboratory settings. Here, we tested the importance of behavioral syndromes to social competence in wild Barbary macaques ( Macaca sylvanus ), an endangered primate with established links between positive social relationships and survival. We studied two groups ( n = 27 individuals) in which behavioral syndrome phenotypes were established in a previous study. Individuals with lower scores for the “excitable” phenotype (roughly equivalent to the “shy-bold” axis in other studies) showed greater plasticity compared to more “excitable” (i.e., “bolder”) individuals in affiliative responses to the immediate social environment, being more likely to initiate grooming with larger numbers of conspecific bystanders present. Less excitable individuals increased their grooming social network connectivity to a greater degree compared to more excitable individuals in periods of higher anthropogenic pressure. During colder weather, less excitable individuals concentrated their grooming network into fewer ties, whereas more excitable individuals slightly increased their number of connections. Any changes in network connectivity in relation to socioecology were small, reflecting the fact that stability in social network position is a common phenomenon in various taxa. Overall, we show that behavioral syndrome phenotypes influence plasticity in affiliative behavior and thus may be a key factor in individual responses to the rapidly changing socioecologies of the Anthropocene.