A Coevolutionary Theory for Communities and Food Web Configurations

Abstract

Any theory of island biogeography must treat both ecological and evolutionary aspects. In spite of this, emphasis has until now been on ecological aspects (e.g., local extinction and immigration of species on isolated islands). Some consideration has been given to the coevolutionary process taking place within a community with a fixed number of coexisting species (i.e., without extinction and immigration or speciation). However, no general theory seems to be available for analyzing coevolution in a community with extinction, immigration and speciation. Fragments of such a general theory arel suggested in this paper. In particular I treat the problem of defining an ecologically and evolutionarily stable island community and food web configuration. For this purpose it is necessary to specify a so-called extended model including the established community together with the potentially invading species. Two important matrices emerge from this analysis: The community matrix (or a-matrix) commonly used in community ecology, and the invasion matrix. These matrices relate ecology and macroevolution to each other. Special consideration is given to the coevolutionary process occurring within a stable community without any species exchange. This model is based on the lag load concept. Analysis of this model provides a linkage between ecology and population genetics. The matrix defining the microevolutionary decrement of the lag loads and the community matrix (or a-matrix) provides this linkage.