Community ecology is complicated and difficult, but global climate change and massive biodiversity loss makes it imperative that we strive toward a coherent understanding of the processes that guide community assembly and structure. In this dissertation I look at how communities are assembled and diversity is maintained in the phytoplankton through both data-driven and theoretical methods, using a trait-based approach to understand the mechanistic basis of community structure and diversity. The first chapter asks what environmental factors drive the distribution of a crucial trait, cell size across a broad spatial scale. The theory chapters are concerned with the role of environmental variation in maintaining diversity. In all, I highlight the importance of temporal variation in shaping the function of communities. |