Butterfly-plant interactions and body size patterns along an elevational gradient in the Manang region of central Nepal

Abstract

Butterflies are widely studied due to their key ecosystem functions. For this reason, they are used in ecosystem assessment, formulating conservation plans and in raising the environmental awareness. Quantification of different factors affecting diversity of butterflies is important for their effective conservation. In this study, we investigated abiotic and biotic factors affecting species richness and community composition of butterflies along an elevational gradient in Manang region, central Nepal. We also tested if butterfly species follow the Bergmann’s rule. A total of 57 butterfly species belonging to 39 genera and 8 families were recorded in the study area. Out of a total of 127 plant species in identified in the study region, only 67 plant species were visited by butterflies as nectar sources. Species richness of butterflies increased with increasing elevation. Species richness was significantly higher in places with shrubs compared to other places and also in autumn than in summer. Species richness of butterflies also depended on composition of plant species occurring at the localities. Butterfly species composition varied among sampling localities. It was also determined by habitat type, elevation, sampling time, plant species and interactions of elevation × time. The relationship between butterfly size and elevation was in the opposite direction than expected according to the Bergmann’s rule. In conclusion, protection of butterfly diversity can only be achieved by protecting different habitats across the diverse physiography of the region and different plant species, in particular herbs and shrubs. Our results do not support the Bergmann’s rule for butterflies along an elevational gradient in our region.