Community structure and ant species diversity across select sites of Western Ghats, India

Abstract

Information available on species composition, richness and diversity of ant communities of Western Ghats is limited. Recognizing this, the study (2010−2013) was undertaken to evaluate richness and diversity of ants in eight sites of Western Ghats, India, with added notes on how it varies on elevation gradient. Spanning across broad altitudinal and latitudinal gradient, selected sites differed greatly for various micro-habitat variables. Using standard collection protocols and employing five collection techniques, 173 species belonging to 65 genera in 10 subfamilies were collected including twenty species published as new to science and two genera and six species reported for the first time from India. Varying among sites, species richness was recorded lowest (S = 29) at Manalar and highest (S = 116) at Periyar Tiger Reserve. With little but significant variations among sites, the Shannon-Wiener's species diversity index (H′) was recorded highest (H′ = 2.60) at Periyar Tiger Reserve and lowest (H′ = 2.11) at Idukki Wildlife Sanctuary connoting that sites with lower richness were not necessarily less diverse. Beta diversity (β-diversity) was lowest (19%) between contiguous sites like Thattekkad Bird Sanctuary and Idukki Wildlife Sanctuary and highest between site Manalar and Periyar Tiger Reserve at 68% suggesting that ant species composition distinctly varied in these sites. Our results indicated that only few species were adapted to full spectrum of environmental variation along altitudinal gradient studied and both species richness and diversity peaked at mid-elevations as against higher elevations wherein it underwent rapid decline. Such behavior is presumably due to favorable ecological conditions at middle altitudes. Our findings rank high as they not only provide baseline data against which futuristic faunal changes could be assessed with respect to perturbations in a biodiversity hotspot but they also could be used to designate ecological sensitivities to various regions of Western Ghats for future conservation programs.