The ecology of subterranean ant communities, communities where most ants live exclusively belowground, remains vastly unknown relative to aboveground ant communities. The thief ants of the genus Solenopsis are a globally abundant and widespread group that is a conspicuous and important part of these belowground communities. Thief ant ecology, including their distribution and diversity at local scales, has rarely been documented. They are purported to practice lestobiosis, a social parasitism form in which they tunnel into other ant colonies and steal larvae.
We sampled the subterranean ant community of central Florida, a region with conspicuously high subterranean thief ant abundance. We asked: (1) Do subterranean ant communities (with an emphasis on thief ants) differ in composition and abundance between flatwood and sandhill habitats? (2) Do soil environmental gradients predict the species diversity of this subterranean ant community? (3) Do these gradients predict the occurrence of thief ant species? We used a stratified-random sampling protocol to sample ants and collect soil environmental variables at each of 32 sampling plots. Non-parametric ordination methods and permutation-based analyses of variance were used to identify associations of species based on habitats. Finally, potential drivers of patterns were identified using statistical models with soil environmental predictors.
Results/Conclusions
Our study yielded 15 species from six genera of which 5 were thief ant species. These 5 Solenopsis species represented 64% of all ants found further confirming the relative abundance of this group of ants. We identified distinct differences in species composition between 2 habitat types with a nonmetric multidimensional scaling analysis (k = 2, stress = 0.126). Significant effects of soil abiotic conditions on the diversity of the subterranean communities were also found. Species-specific logistic regressions indicate strong evidence of soil abiotic conditions (soil moisture and temperature) predicting species occurrence as possible a form of environmental filtering.
This study finds that thief ants dominate in abundance belowground relative to other co-occurring ants in the subterranean environment and further supports the general abundance and prevalence of this group. We also show evidence that soil environmental conditions may drive patterns of diversity and distribution for this subterranean community. Biotic effects among these species could be important given their purported lestobiotic behaviors that may play a role in regulating other ant species at a population level. Finally, this study also adds to a developing field within ant ecology as subterranean ant communities may represent the final frontier for unexplored ant biodiversity.