Two schools of thought on community structure have developed largely in parallel with little integration. Local-scale ecologists consider factors that influence population demographic rates (species interactions, physical factors), while others think regionally about dispersal, extinction, immigration, and speciation. We still know very little about which processes exert the most influence over species diversity, composition, and trophic structure. My work in lakes suggests ways in which local and regional processes interact in shaping assemblages. Large-bodied organisms at high trophic positions show signs of being more limited by dispersal in their distributions than small species near the base of the food web. The meta-population behavior of top predators like fishes promotes regional diversity at lower trophic levels, leading to a feedback between processes at local and regional scales. I discuss ways of integrating across scales to detect the roles of mechanisms operating within versus among habitats.
Jon Shurin is interested in the connections among population, community, and ecosystem ecology. He uses field experiments, broad scale surveys and theory to address questions like the following: