Are Primates Ecosystem Engineers?
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Animals can play important roles in structuring the plant communities in which they live. Some species are particularly influential in that they modify the physical environment by changing, maintaining, and/or creating new habitats; the term ecosystem engineer has been used to describe such species. We here assess the two major foraging strategies of primates, frugivory and folivory, in terms of the potential for primates to function as ecosystem engineers. We argue that whereas the role of primates as seed dispersers has received a great deal of attention, the potential role that folivorous primates play in structuring their environment through herbivory has received much less attention. Further, while quantifying if frugivorous primates are ecosystem engineers through their seed dispersal has proved very difficult, it is not as difficult to ascertain whether folivorous primates are ecosystem engineers. We document situations in which folivorous primates act as ecosystem engineers by 1) eating the leaves and/or bark of trees to the extent that they kill trees, 2) feeding on trees to the degree that they slow their growth relative to nonpreferred tree species, 3) eating the flowers of species to the extent that it does not set fruit, or 4) feeding on plants in such a way as to increase their productivity and abundance. Because evidence from the literature is very limited, where possible we present new evidence of these processes from the colobus monkeys at our long-term field site in Kibale National Park, Uganda. We conclude by discussing promising research programs that could be established to refine our understanding of the role primates play in shaping the structure of plant communities, especially tropical forests.
KeywordsHerbivory Keystone modifier Kibale National Park Seed dispersal Tree mortality
Funding for the research in Kibale was provided by the Canada Research Chairs Program, Natural Science and Engineering Research Council of Canada, and National Geographic. M. D. Wasserman was supported by a Tomlinson Post-Doctoral Grant, J. F. Gogarten was supported by a Graduate Research Fellowship form the National Science Foundation, and T. Bonnell was supported by an FQRNT Fellowship. Thanks to Richard Wrangham for initiating the phenology monitoring with C. Chapman in 1989. Permission to conduct this research was given by the National Council for Science and Technology and the Uganda Wildlife Authority. We thank Lauren Chapman, Marco Campenni, Aerin Jacob, and Amy Zanne for helpful comments on this research.
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