Oxytocin and Affiliative Behavior in Male P. Verreauxi at Kirindy Mitea National Park, Madagascar

Abstract

Though social behavior is widespread in primates, patterns and drivers of affiliation are not well understood, especially in males and strepsirrhine species. Recent studies have identified the role of oxytocin, a neuropeptide involved in maternal and pair-bonding behaviors, in general affiliation. However, these studies have exclusively used haplorrhine species and primarily rely on laboratory or captive work. Here, we use wild male Verreaux’s sifaka (P. verreauxi), a group living lemur species with opposite and same-sex affiliative behaviors, to investigate the association between oxytocin (OT) and affiliative behavior. We collected behavioral data and urine samples from individually marked Verreaux's sifaka in Kirindy Mitea National Park, Madagascar between 2018 and 2019. In the Laboratory for the Evolutionary Endocrinology of Primates (LEEP) we used ELISA Arbor Assays OT kits to conduct urinary OT analysis on 127 samples. We compared behavior, OT concentrations, and the relationship between the two across two seasons: mating and non-mating. We found that OT is higher in the non-mating season, while affiliative behaviors are more frequently observed in the mating season. In the non-mating season, there was a significant negative association between OT and affiliative behavior. Our results demonstrate seasonal patterns of both OT and affiliative behavior and a lack of association between these two variables, suggesting further investigation of the understudied roles of OT across seasons, and other potential hormonal mechanisms for seasonal differences in behavior.