Termite cohabitation: the relative effect of biotic and abiotic factors on mound biodiversity

1. Termites are important ecosystem engineers that improve primary productivity in trees and animal diversity outside their mounds. However, their ecological relationship with the species nesting inside their mounds is poorly understood. 2. The presence of termite cohabitant colonies inside 145 Cornitermes cumulans mounds of known size and location was recorded. Using network-theoretical methods in conjunction with a suite of statistical analyses, the relative influence of biotic and abiotic drivers of termite within-mound diversity on the composition and species richness of the termite community was investigated, specifically builder presence and physical aspects of the mound. 3. We found that richness inside the mound increases with mound size, and the species similarity between mounds decreases with distance. The physical attributes (abiotic drivers) of termite mounds (size and relative distance to other mounds) are the strongest predictors of termite species richness and composition. The biotic driver (presence of a builder colony) has an important, though smaller, negative effect on within-mound termite species richness. 4. The findings suggest that the termites' physical manipulation of their environment is an important driver of within-mound community diversity. More generally, the approach taken here, using a combination of statistical and network-theoretical methods, can be used to determine the relative importance of abiotic and biotic drivers of diversity in a wide range of communities of interacting species.