Patterns of Ant Species Richness and Composition in Deccan Inselberg-Matrix systems of Karnataka

Abstract

My study looked into patterns of ant species richness and composition of Deccan inselbergs and surrounding human altered matrix (natural habitat, mango plantation) in Ramanagara taluk, Karnataka, in a bid to recognize their ecological and conservation potential. Ants were chosen as the model taxa, due to their micro-habitat specificity, to better understand environmental gradients and related faunal associations at different scales. Pitfall traps were used as the sampling methodology for ants, and habitat variables were collected at each trap; ants were identified until morphospecies level within respective genera. Data analysis included understanding habitat differences, patterns of species richness and composition, and relating these aspects. The results showed that inselbergs were distinct in terms of habitat structure as compared to the matrix, with the latter showing less vegetation complexity (lesser in mango plantation). While matrix and inselberg showed comparable levels of ant richness, delving deeper it was seen that natural habitat within matrix showed significantly higher richness as compared to the species poor, uneven mango plantation ant assemblage. Similarly, inselbergs and matrix showed similar average composition of their respective ant communities. However closer inspection showed that natural habitat and plantation, when compared separately with inselbergs, showed compositional dissimilarity to greater magnitude. Habitat variables, while statistically significant in their relationship with patterns of ant composition and richness at finer scales, explained a minimal amount of total variation seen in both. Inselbergs, as understood through this study, are not “barren wastelands”, but on the contrary are important reservoirs of regional diversity. In light of rapid human alteration of the surrounding matrix and threats like quarrying, invasive species, inselbergs and the low lying natural habitat need to be given greater conservation importance. This study is hopefully just one of many that are required to further assess the conservation and ecological potential of these amazing ecosystems.