Department of Anthropology, The Ohio State University
April 14, 2016 3:15, A 602
Data on various primate species indicate females attempt to associate more frequently with dominant males. Few studies, however, consider whether male rank trajectory (or potential for males to change ranks over time) influence male-female interactions. Although it can be difficult to assess rank trajectory in species expressing infrequent rank-turnovers, the Elo rating system offers a numerical measure of both rank and rank trajectory and is an important new tool for evaluating primate social structures. We use this method to assess dominance hierarchies in olive baboons (Papio hamadryas anubis) from approach-retreat interactions, and test whether females preferentially associate with males gaining rank in their social groups. We recorded all interactions between focal females (n = 19) and adult males (n = 29) in three groups at Gombe Stream National Park over two study periods. Generalized linear mixed models were employed to test for an effect of rank, rank trajectory, age, and parity on behaviors indicative of mate choice in this species. Male rank trajectory had the strongest effect on female approaches (n=105, F2,94=4.381, p=0.015) and grooming bouts (n=105, F2,94=5.093, p=0.008). Surprisingly, females affiliated more frequently with males categorized as “neutral” (i.e., neither increasing nor decreasing in rank) based on trajectory scores. These males also tend to be more aggressive towards females (n=109, F3,98=2.228, p=0.090). Our data provide further evidence of the interactions of male-male competition and female choice in this species and indicate rank trajectory should be considered when assessing social interactions in primate species more generally.
We would like to thank the following institutions for funding this project: The Leakey Foundation, International Primatological Society, American Society of Primatologists, Sigma Xi, and The Ohio State University.