1Department of Anthropology, Stony Brook University, 2Cognitive Ethology Laboratory, German Primate Center, 3Courant Research Center Evolution of Social Behavior, University of Goettingen
Thursday 1:45-2:00, Ballroom B
Ecological models of female social relationships predict an association between competition and female agonistic relationships. If rank provides advantages in within-group competition, despotic dominance relationships should result. Measures of rank-related energetic gains are rare, however, and the variation in dominance relationships across all nonhuman primates is unknown. As an initial step to close this gap, we provide the first large-scale comparative analysis of female dominance relationships and hierarchies across the primate order, investigating if despotism varies along a predicted despotic-egalitarian gradient. Data were derived for 54 groups from 26 species of Platyrrhini, Cercopithecinae, Colobinae, and Hominoidea, including groups of at least 6 females from wild populations (strepsirrhine groups were too small to be included). We analyzed hierarchy characteristics of despotism, including directional consistency, linearity, and steepness, as well as types of relationships (transitive, inconsistent), sampling effort, and female group size. Principal component analysis extracted one axis related to directional consistency and a second related to linearity and steepness. In contrast to common expectations, the latter two factors were indistinguishable and their value strongly dependent on sampling effort. Two additional axes related to sampling effort and female group size. Variation across groups and taxa was primarily apparent in the directional consistency axis. Discriminant function analysis showed differences in consistency (but not linearity or steepness) for cercopithecines and hominoids (more despotic) versus platyrrhines and colobines (less despotic). Contrary to common assumptions, variation in despotism relates mainly to directional consistency, but less so to linearity or steepness, and includes a phylogenetic signal.