Coevolution and Community Organization in Three Habitats

Abstract

This paper presents a game theoretic model of habitat selection. The ESS approach considers the types of community organizations that emerge from coevolutionary responses to three distinct habitats. Behaviorally, foragers may be one-habitat selectors, two-habitat selectors, or opportunistic ; morphologically, foragers possess traits that represent tradeoffs among performances in the three habitat types. The ESS of the model takes on any one of ten forms (I one-species community, 4 two-species, and 5 three-species). Communities exhibit nested niches, ghost of competition past, centrifugal organization, and combinations of organizations within the same community. Environmental factors such as the scale of habitat patchiness (fine-grained to coarse-grained) and habitat-specific resource productivities determine the community organization of the ESS. Along the continuum of fine- to coarse-grained, the community changes from a single opportunist species to three one-habitat selector species exhibiting the ghost of competition past. Increasing the encounter rate on just one habitat type promotes communities displaying nested niches with an opportunist, two-habitat selector, and one-habitat selector species. Rendering productivities lopsided encourages centrifugal organization. The varied outcomes of this single, simple model of habitat selection suggest that an understanding of the community organization of habitat selectors will require joint study of the organisms' behaviors, environmental conditions, and the species' evolutionarily feasible aptitudes on the different habitats.