Abstract # 219:

Scheduled for Monday, September 21, 2009 02:45 PM-02:55 PM: Session 23 (Mission Bay Ballroom AB) Oral Presentation


THE EVOLUTIONARY IMPLICATIONS OF FOOD COLLECTION AND TRANSPORT FOR CONSTRAINTS ON FORAGING GROUP SIZE.

D. L. Hannibal
University of Oregon, Department of Anthropology, Eugene, OR 97403-1218, USA
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Cercopithecines are the only primates, other than humans, capable of collecting and transporting large quantities of food. Studies demonstrate that cercopithecine cheek pouches serve a feeding competition role. Cercopithecines also live in larger groups than other primates. Large group size aids intergroup competition over resources, but increases intragroup competition. I investigate whether cheek pouches release group size constraints. Group size is variable and adjusts to competition pressures, while body size is relatively fixed and a fundamental adaptation influencing a species dietary strategy. Male body size, however, can be driven by intrasexual competition. Therefore, analyses use female body size as the independent variable and foraging group size as the dependent variable. Regression analyses [α=0.05] demonstrate female body size predicts foraging group size among frugivorous cheek-pouching primates [r2=0.47], with group sizes as large at 90, but not among non-cheek-pouching frugivorous primates [r2=0.01], with group sizes limited to 25. For all categories (non-human primates, non-human anthropoids, frugivorous anthropoids, monkeys, frugivorous monkeys) analyzed, female body size predicts group size among cheek-pouching, but not non-cheek pouching, non-human primates. This adaptation, allowing rapid collection and transport of food away from competitors, allows cercopithecines to live in larger groups than most other primates. The results of this study support an ability to collect and transport large quantities of food as a key component in the evolution of large group sizes.