1Department of Evolutionary Anthropology, Duke University, 2Department of Structural Biology, Stanford University School of Medicine, 3Vaccine Research Center, National Institutes of Health, 4Sanofi, Sanofi, 5Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, 6School of Human Evolution and Social Change, Arizona State University
April 14, 2016 10:15, A 706/707
Male chimpanzees sometimes employ sexual coercion to constrain female choice and increase their reproductive success. Alternatively, they may sometimes obtain increased reproductive success by trading grooming for mating opportunities. The efficacy of these strategies likely varies between both individuals and communities according to demography and male dominance structure. In Gombe National Park, sexual coercion, in the form of long-term patterns of aggression, is associated with increased reproductive success primarily for high-ranking males. However, many males manage to sire offspring without being high ranking or highly aggressive towards females. We analyzed a 17-year sample of behavioral and genetic data from Gombe to test the hypothesis that affiliative behavior increases male reproductive success. In a preliminary analysis, we found that high-ranking males were more likely to sire offspring with females who they groomed frequently (GLMM, p = 0.04), controlling for female age, dyadic relatedness, and dyadic rates of long-term aggression. In a separate analysis, we found that all males were more likely to sire offspring with females with whom they associated at high rates (GLMM, p < 0.01), controlling for female age, dyadic relatedness, dyadic rates of long-term aggression, and male rank. Thus preliminary results suggest that male-female grooming and affiliation are positively associated with male reproductive success, independent of coercive aggression, and may represent a viable alternative to sexual coercion. Future work will add additional reproductive events to increase sample size and employ an information-theoretic approach to determine best predictors of paternity.
Data collection: Jane Goodall Institute, long-term database construction: NSF (DBS-9021946, SBR-9319909, BCS-0452315, IIS-0431141, IOS-LTREB-1052693), genetic analyses: NIH (R01 AI058715), Feldblum: NSF GRFP (DGE-1106401), Wroblewski: Kirschstein Award (NIH F32 AI085959-03).