Impacts of Migration on Pond Food Web Structure: Insights From Metacommunity Biology and Implications for Multi-Scale Diversity

University Of Texas At Austin, Austin TX

Investigators

Abstract

The importance of ecological dispersal on community processes is widely recognized. However, neither the magnitude of migration effects on species-rich communities, nor the interplay of dispersal and local community processes, is well understood. Perhaps the most appropriate framework for exploring the consequences of migration to the community and region is the metacommunity, as it acknowledges multi-scale processes influencing community dynamics. Metacommunity biology addresses the impacts of inter-community dispersal, and links local to regional processes in a spatially explicit context. Emergent metacommunity theory indicates that dispersal rate can dramatically affect local and regional species richness, and ecosystem functioning, yet uses simplistic food web models to do so. In contrast, empirical metacommunity investigations employ multiple trophic levels but unsuccessfully isolate local mechanisms interacting with migration. Our research addresses the apparent disconnect between the two methods, and takes a multi-trophic and mechanistic approach to evaluating the effects of dispersal and community-level spatio-temporal heterogeneity on pond food webs. Results indicate that dispersal rate alters species richness at local and regional scales, and affects trophic structure. The proposed work extends these concepts and incorporates life-history trade-off theory into a metacommunity framework. By synthesizing mechanistic, metacommunity, and trade-off theory the research may provide novel insight into species incidence and coexistence. Further, the research has strong implications for conservation as fragmented landscapes become increasingly prevalent, and local and regional biotas modified. Ultimately, it is important to isolate and identify drivers of local and regional species richness in order to maintain biotic integrity at the global scale.