Butterfly diversity along the elevation gradient of Eastern Himalaya, India

Abstract

AbstractThe species richness pattern along spatial scales (latitudinal or elevational) forms useful tools in understanding diversity gradients and their underlying mechanisms. Understanding elevational diversity patterns of biodiversity have strong conservation implications. Himalayas are unique systems in exploring such gradients as they harbor tallest mountains in the world. Here, we explored the elevational pattern, its underlying causes, turn over rate and range size distribution of butterflies in Sikkim, Eastern Himalaya, India. We followed fixed width point count method for sampling butterflies covering 1014 points spread over 23 transects along the elevation gradient (300–4700 m) in Sikkim. Data on environmental factors and habitat parameters were obtained from our published literatures of the same study system. During this study we observed a total of 2749 butterflies representing 161 species and six families. Species richness pattern of butterflies followed declining trend along the elevation gradient with a hump at around 1000 m. Various environmental factors and habitat variables correlated strongly with the species richness and abundance of butterflies. Among the set of factors, mean annual temperature and actual evapotranspiration remained the most important determinants reflecting the importance of energy and productivity for butterfly distribution in the Eastern Himalayan elevation gradient. Butterflies showed high turnover along the gradient. Elevational range profile of butterflies showed that around 38.5 % species restricted below 2000 m elevation. We observed that low elevation areas are important for conservation of butterflies in the Eastern Himalaya although entire elevation gradient is crucial for small range‐sized species.