Date of this Version
International Journal of Primatology (October 2005) 26(5): 1,017-1,037. DOI: 10.1007/s10764-005-6456-2.
Investigations of coevolutionary relationships between plants and the animals that disperse their seeds suggest that disperser-plant interactions are likely shaped by diffuse, rather than species-to-species, coevolution. We studied the role of dietary plasticity in shaping the potential for diffuse coevolution by comparing dietary fruit preferences and seed dispersal by 3 species of spider monkeys (Ateles spp.) in 4 moist forests in Colombia, Ecuador, Panama, and Surinam. In all forests, spider monkeys were highly frugivorous and preyed upon seeds of few species. We estimated dietary use of fruiting taxa based on absolute consumption and preference, which accounts for resource availability. Of the 59 genera that comprised the 20 most frequently consumed genera summed in each forest, only 3—Brosimum (Moraceae), Cecropia (Cecropiaceae) and Virola (Myristicaceae)—ranked within the top 20 at every forest. Most genera were within the 20 most frequently consumed at only 1 or 2 forests. Based on preferences, only 4 genera ranked in the 20 most-preferred in all 4 forests: Brosimum, Cecropia, Ficus (Moracae), and Virola. Patterns in fruit consumption and preference at the familial level were similar in that only 2 families—Myristicaceae and Moraceae—were in the 10 most-consumed or most-preferred in all 4 forests. Interforest variation in plant specific composition and abundances and supra-annual fruiting phenologies, combined with dietary flexibility of Ateles spp., may partly explain these patterns. Our results suggest that variation in plant community structure strongly influences dietary preferences, and hence, seed dispersal by spider monkeys. Thus, diffuse coevolution in spider monkey-plant relationships may be limited to few taxa at the generic and familial levels.