Butterfly diversity along the elevation gradient of Eastern Himalaya, India

Abstract

The 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.

Spatial distribution of butterfly (Lepidoptera: Papilionoidea) along altitudinal gradients at Gunung Ledang National Park, Johor, Malaysia

“…This pattern corresponded with the hypothesis that indicated the species richness of insects peak at the lower elevations [28]. Similarly, butterfly species number declined with increasing elevations in the Eastern Himalaya, India due to environmental factors and habitat variables [1]. Environmental biotic factors such as abundance and quality of host plants, physical characteristic including climate, landscape and elevation, and disturbances both human activities and wildfire could influence butterfly's populations and distribution [4].…”

“…and experiences lower temperature and more stunted vegetation as the elevation increases [33]. The previous study reported butterfly richness decreases as the altitude increases due to environmental factors and habitat variables [36,1]. Nonetheless, the mountain is an area of great biological interest as it houses high number of endemic species and is Pleistocene refuges especially for invertebrates [22].…”

Correlates of avifaunal diversity along the elevational gradient of Mardi Himal in Annapurna Conservation Area, Central Nepal

“…However, faunal assemblage along the elevational gradient is not consistent. Invertebrates like ants and butterflies (Bharti et al 2013;Acharya and Vijayan 2015) show mid-domain effects, whereas, poikilothermic vertebrates such as amphibians and reptiles exhibit monotonic decline in richness towards higher elevation (Chettri et al 2010;Khatiwada et al 2019). Birds are more complex in elevational richness pattern; they display mid domain effects in some mountains of the Himalaya (Acharya et al 2011b;Paudel and Šipoš 2014) whereas monotonic decline has been observed in the others (Basnet et al 2016).…”

Climate and plant structure determine the spatiotemporal butterfly distribution on a tropical mountain

“…By contrast, β‐diversity changed in a different way; it was greater at elevations with lower temperatures, higher humidity, and lower precipitation or high temperatures, lower humidity, and higher precipitation. Most studies examining the mechanisms responsible for the distribution of butterflies have concluded that temperature and/or rainfall explain species richness (Acharya & Vijayan, 2015, Sorch et al 2003, Ribeiro et al., 2010) and have related these variables to the production of leaves (food) and butterfly physiology (Peters et al., 2016; Ribeiro et al., 2010, Bennett et al, 2015). The relationship between butterfly diversity and climate is complex, and it changes between areas and altitudes.…”