FIG 5 .

Summary figure illustrating our hypotheses. The metacommunity represents the total group of possible organisms that could assemble into our local communities. The black lines illustrate the total “ecological processing” that generates the local communities, with the blue, white, and purple boxes indicating specific ecological filters within a given location. Arrows adjacent to the colored bars represent interactions that enhance specific processes. For example, stable geochemistry enhances homogenizing selection. The red-blue gradient arrow represents a range of redox conditions from reducing to oxidizing. The red and green boxes indicate the measured ecological processes that must occur between the wells to obtain the observed results (dispersal limitation between the Athens and Licking locations and variable selection between the Greene aquifer and the other two locations).