R code for species richness calculations

The R code estimates species richness and produces CHAO estimators for different distance bins from the central Azteca Nest.

Here we analyze a system of diffuse competition in an ant community in a tropical coffee landscape in southern Mexico. The community is constrained by space in that the dominant competitor (Azteca seriaceasur) has a limited range of influence within which it excludes most other species, but outside that range, the other species may all persist. We use a simple dynamic model in which variable A, the dominant competitor, competes strongly with variable S, the collection of all other species in the system, the latter acting as a single strong competitor in the context of diffuse competition. Two qualitatively distinct outcomes are expected depending on the strength of competition: 1) a simple monotonic increase in species richness as the distance from the Azteca nest increases or 2) a range of distance from the nest in which there is bi-stability (either A dominates or S dominates), bookended by critical transitions. Studying five specific nests in wet and dry seasons over a two-year period, we find evidence for the bi-stability situation. Implications for metacommunity structure are discussed.