Consistent individual variation across interaction networks indicates social personalities in lemurs

Abstract

Group members interact with each other in multiple ways, ranging from aggression to affiliation. It is not known, however, whether an individual's suite of social behaviors consistently co-varies through time and across different types of social interactions. Consistent social behavior would be advantageous in groups, especially when individuals need to remember conspecifics' social roles and preferences in order to keep track of group members' social relationships and predict their future behavior. Here, we address whether social behavior of individual ring-tailed lemurs (Lemur catta) is consistent through time and across four behaviors (aggression, grooming, contact calling, scent marking). We quantified variation in social behavior through four network centrality measures (out-degree, out-strength, betweenness, and eigenvector centrality). Comparing networks across two years revealed that network centrality remained consistent between years. Centrality was also consistent across networks: Lemurs with high centrality in one network also had high centrality in the other networks, even when we controlled for sex-based variation in behavior. Thus, regardless of their sex, some individuals were highly social in all four behaviors. They frequently groomed others, initiated aggressive interactions, and responded to others' contact calls and scent marks. Lemurs also had preferred social partners, and frequently interacted with the same individuals across multiple types of social behaviors and across years. In particular, lemurs frequently responded to the contact calls and the scent marks of the conspecifics they had frequently groomed. Together, these results demonstrate that individual variation in social behavior is not context specific, but instead persists through time and across multiple social interactions. Such consistent behavior provides evidence for social personalities, which may influence individuals' interaction styles including how socially active they are and with whom they interact.