Structuring of aquatic ecological communities

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Ecological communities have been argued to represent either random subsets of the regional species pool, or a specific subset due to a variety of interacting effects ranging from biotic interactions (e.g. competition, predation), abiotic factors (a species intolerance to particular environmental conditions), and historical factors (e.g. colonization, evolutionary relatedness). I propose to examine fish communities in order to further our understanding of the role of these various factors. Lake and stream fish communities from within Ontario and at a continental scale will be tested to determine the relative importance of the biotic similarities due to their evolutionary similarities. I will determine the role of the abiotic environment in filtering out particular combinations of species due their differences or similarities in their habitat requirements, relative to the role of species interactions (e.g. competition) as determined through examining the composition of communities based on their morphology, their functional relationships (similarity in feeding, reproduction, behaviour), and their phylogenetic relationships. As evolutionary history likely results in more closely related species sharing morphological, functional, and environmental traits, than more distantly related species, the inclusion of phylogenetic relatedness will allow a more informative test of whether communities do represent random subsets of species or whether biotic or abiotic factors appear to have a greater regulatory role in determining their composition.