Species turnover: the case of stream amphibians of rainforests in the Western Ghats, southern India KARTHIKEYAN VASUDEVAN 1 , AJITH KUMAR 2, * and RAVI CHELLAM 1 1 Wildlife Institute of India, P.O. Box 18, Dehra Dun 248-001, India; 2 Salim Ali Centre for Orni- thology and Natural History, Anaikatti, Coimbatore 641-108, India; *Author for correspondence. Present address: Wildlife Conservation Society - India Program, Centre for Wildlife Studies, # 823, 13th Cross, Block VII, Bangalore 560 082, India (e-mail: ajith@wcsindia.or) Received 26 May 2003; accepted in revised form 19 August 2004 Key words: Abundance, Anurans, Beta diversity, Conservation, Species richness Abstract. We examined species turnover in stream amphibians in rainforest in two hill ranges (Ashambu and Anamalai Hills) in the Western Ghats in south India. In each hill range, six stream segments (100 m in length) belonging to three drainage or rivers were surveyed three to four times in three seasons over 1 year. Species turnover (using 1-Sorenson’s index) was estimated between all possible pairs of sites at three spatial scales – within drainage, between drainage and between hill ranges. Similar matrices were also developed for altitudinal difference and geographic distance between sites. A total of 30 species in four families were recorded from 3681 individuals. The hill ranges differed significantly in the composition of the stream community at both the species and family levels. Within the hill range, species turnover was correlated with altitudinal difference and not with geographic distance. Anamalai Hills had a greater species turnover than Ashambu Hills, both within and between drainage. There was also a high turnover between these two hill ranges, with only two shared species. This turnover explains the fact that only 30–40 species have been reported from different hill ranges, although regional diversity is high with about 130 species. The turnover also predicts that several undetected species should occur in hill ranges and drainage that have not been surveyed. The conservation model for mammals and birds, consisting of a few large protected areas, may not adequately address the conservation requirements of amphibians. Protection of rainforest frogs may require many protected areas in different drainages. Introduction Amphibian diversity and abundance varies significantly among neotropics, Africa and Southeast Asia which has been attributed to differences in litter fall rates, mast fruiting, heterogeneity within regions, breeding habitat constraints, and geological history (Allmon 1991). The variation in amphibian diversity within the Amazon is related to altitude, topography, and rainfall, with his- torical biogeography and reproductive modes (Duellman 1999). Reproductive mode is particularly important in mountainous habitats, where the ubiquitous mode of reproduction in amphibians (egg and tadpoles in lentic water) may be rare or even absent (Duellman 1999). However, the influence of hill streams habitats on local and regional species diversity of amphibians has been little examined. Due to, greater atmospheric humidity and varying physical features, Biodiversity and Conservation (2006) Ó Springer 2006 DOI 10.1007/s10531-004-3101-x