The Coevolution of Competitors in a Community Context

Peter Abrams (April 7, 2011)

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Most theoretical work on the evolution of competing species has used models having the minimum number of species (i.e. two), and has not represented either enemies or resources of those two consumer species. Empirical studies of character displacement involve species that share multiple resources, and usually multiple predators as well. Although some prominent experimental systems involve only two competitors, the natural communities where these species occur often have more. My talk will concentrate on two types of extension of the current body of theory. The first is models of the evolution of competitors in a community or food web context. This illustrates the importance of ecological interactions on other trophic levels when determining the response of one species to changes in a putative competitor on its own trophic level. The second is the study of multi-species coevolution under such a community context. It has long been known that the impact of one competitor on a second may be positive when the community contains many competitors; this occurs via indirect effects on other mutual competitors. However, the implications of such positive population-level interactions on predictions of character displacement have not been explored. If removal of one competitor causes niche shifts of similar competitors, will large magnitude shifts be propagated throughout the competitive community? These and other aspects of the coevolution of species on a given trophic level will be considered. Where possible, examples of relevant plant-insect systems will be discussed.