Dominance in ring-tailed lemurs: Development, acquisition, and maintenance

Dominance rank is an important component of everyday life for group-living animals because it affects access to resources such as food and mates, which affect overall reproductive success. Despite the importance of dominance rank, few studies have investigated the development and acquisition of dominance in immature individuals. The studies that have been conducted have focused on female-bonded male-dominant species in which maternal rank is inherited. Therefore, little is known regarding other dominance systems and species in which maternal rank is not inherited. Additionally, although hormonal correlates of dominance have been studied in adults, very little is known regarding hormonal correlates of dominance in immature individuals. Although social relationships among adult females have been investigated in female-bonded societies, there has been little investigation of these relationships in species not characterized by male dominance over females.;To address these issues, a comparative study was conducted on a population of ring-tailed lemurs in their natural habitat at the Beza Mahafaly Special Reserve in southwestern Madagascar and a food-provisioned population on St. Catherines Island, Georgia, USA. Ring-tailed lemurs, like the majority of lemur species, are characterized by female dominance, i.e. the ability of all females to elicit submissive behavior from all males. The specific aims were to address the proximate mechanisms underlying the development, acquisition, and maintenance of dominance in ring-tailed lemurs. The behavioral and hormonal correlates of the development and acquisition of dominance were investigated among peers during infancy and among reproductively mature individuals as they entered the adult hierarchy. There were sex-specific strategies in grappling behavior, which determine dominance acquisition among infants. The dominance hierarchy was not stable from infancy through the juvenile period. Infants also showed sex-specific hormone patterns typical of adults. There were behavioral and hormonal changes at the period of female-dominance onset at reproductive maturity. Social connectedness among adult females was investigated in relation to social support to determine if these two factors are used to maintain social status. Females that were more socially connected led targeted aggression events, but social connectedness was not related to aiding behavior. Females that were evicted from their groups during targeted aggression events were stably unconnected prior to eviction. These findings greatly expand the current knowledge of dominance relationships; particularly by showing how factors associated with acquisition and maintenance of dominance may change in female-dominant societies compared to the well-studied male-dominant societies.