In the last 160 years, researchers interested in the drivers of species richness patterns have come a long way in determining what factors greatly affect species richness at local and global scales. Area, energy, and heterogeneity are often invoked as the primary drivers of species richness patterns. Yet, there are few tests of how these factors interact to affect patterns of species richness. I use experimental freshwater communities and a model zooplankton system to better understand the mechanisms by which environmental factors interact to affect species richness patterns.