Figure 1.

Models of niche overlap for three coexisting species driven by different mechanisms of interspecies interaction. Circle size reflects productivity of these species during interactions. When resources are shared and limiting (left panel), niche overlap is considerable and species compete, which decreases productivity of each species and the overall community. When species inhabit complementary niches with alternative resources (middle panel), niches do not overlap and the antagonistic effects of competition are minimized, leading to increased community productivity. When species are facilitative (right panel; larger circles), the presence of one species enhances the fitness of the others, which increases productivity in a synergistic manner.