Abstract # 126:

Scheduled for Sunday, September 18, 2011 10:30 AM-10:45 AM: Session 17 (Meeting Room 408) Oral Presentation


A. Di Fiore1,2,3 and A. Link1,2,3,4
1New York University, Department of Anthropology, New York, NY 10003, USA, 2New York Consortium in Evolutionary Primatology, 3University of Texas at Austin, 4Universidad de los Andes, Bogota, Colombia
     We studied male mating behavior and reproductive success in one group of wild spider monkeys by collecting systematic data on sexual behavior from nonjuvenile group members and by determining paternity for 24 offspring born over a 10+ year period using a panel of variable microsatellite markers. Over the main behavioral sampling period (2005-present), several males copulated with each female during estrus, and all nonjuvenile males were observed mating. Copulations were secretive, taking place only during consortships, and we observed no extra-group matings or aggression among males over females. With one exception, paternities for all offspring were assigned to males residents. Most males sired at least one offspring, although reproduction was skewed toward one or two males during some portions of the study. In all cases where sires were determined for a female's successive offspring, different males were assigned paternity. Male spider monkeys are philopatric and cooperate in agonistic interactions with other groups. Reproduction by related males and cooperation among male kin potentially increase male inclusive fitness, which could explain why aggressive male mating competition is rare. Paternity success may nonetheless vary because of female choice, or because males enjoy differential success in employing alternative mating tactics. At the same time, females mate with multiple males, potentially to confuse paternity as a counter-strategy against infanticide or to increase males' incentives to participate in cooperative group defense.