Understanding patterns in ant (Hymenoptera: Formicidae) species richness and co-occurrence across elevation gradients

The Eaglenest wildlife sanctuary (EWS) in the western part of Arunachal Pradesh and part of the Eastern Himalaya biodiversity hotspot is a promising area to study biodiversity distribution across elevation gradients. The EWS offers steep elevation gradient, and almost continuous tracts of forest evergreen forests from base to summit. The vegetation changes from Evergreen at the lowest elevation to Rhododendron stands towards the highest elevation of about 3000m. The large variation in environment indicates that the area can be home to a large number of species. This presents an opportunity to study how different groups of plants and animals respond to similar changes in the environment. This was one of the objectives of our research. We chose to study ants because of diverse ecological roles ants play. They assume multiple roles such as predators seed dispersers and symbiotic partners of other animals. In a way, they are like the swiss knifes of the insect world. There are a large number of ant species with their own specific requirements. This makes them an ideal system for our study. For our work, we sampled of ant communities distributed at different elevations across steep and undulating mountain slopes of EWS. This is the first ecological study of ants in the EWS. We have recorded more than 200 species from the sanctuary. We are at present analysing the data, and we only have preliminary results. Our results indicate a decrease in species richness from low to high elevations. There are close to 90 species at the lowest sampling site while only six species at the EWS ridge at 2400m. We hope that by finding mechanisms behind the patterns we observe in Eaglenest will lead to interesting insights into the ecology of the eastern Himalaya. During our work, we have encountered some really interesting ants like the jumping ant (Harpegnathos sp.) or the Dracula ant (Stigmatoma sp.). This ant gets its name as the workers feed on their own larvae.