Primates on the Menu: Direct and Indirect Effects of Predation on Primate Communities

Abstract

Predation has almost certainly driven morphological, behavioral, and cognitive changes in primates throughout their evolution. However, the extent to which predation has affected the coexistence of primates within ecosystems has rarely been examined. Recent evidence of “top-down” and indirect effects of top predators on ecological systems suggests that the effect of predation as a structuring mechanism for primate communities should be reconsidered. I review direct and indirect effects of predation on communities and suggest how these may have shaped aspects of primate communities, particularly species richness. I also include preliminary analyses of mammalian prey communities across biogeographic regions to investigate the possible effects of shared predation on primate communities. Keystone predation in which a shared predator feeding on competing consumers facilitates the coexistence of multiple consumer species could theoretically affect the species richness of primate communities. Results from my preliminary analyses show that sites with fewer preferred alternative mammalian prey species had communities with more primate species in Africa and the Neotropics, but not in Asia or Madagascar, where preferred alternative prey did not differ between sites and where primate species made up larger percentages of prey communities. These results suggest that predation pressure on the mammal communities in Africa and the Neotropics may indirectly affect competitive relationships, potentially reducing competitive exclusion. Further research that includes details of prey abundance, rates of predation in specific communities, and human effects on predators and prey in each region is needed to understand better the impact of predators on primate communities.