Elevational gradients of diversity for lizards and snakes in the Hengduan Mountains, China

Abstract

Comparing elevational gradients across a wide spectrum of climatic zones offers an ideal system for testing hypotheses explaining the altitudinal gradients of biodiversity. We document elevational patterns of lizard and snake species richness, and explore how land area and climatic factors may affect species distributions of lizards and snakes. Our synthesis found 42 lizard species and 94 snake species known from the Hengduan Mountains. The lizards are distributed between 500 and 3500 m, and the snakes are distributed between 500 and 4320 m. The relationship between species richness and elevation for lizards and snakes is unimodal. Land area explains a significant amount of the variation in lizard and snake species richness. The cluster analysis reveals pronounced distinct assemblages for lizards and snakes to better reflect the vertical profiles of climate in the mountains. Climatic variables are strongly associated with lizard and snake richness along the elevational gradient. The data strongly implicate water availability as a key constraint on lizard species richness, and annual potential evapotranspiration is the best predictor of snake species richness along the elevational gradient in the Hengduan Mountains.

Elevational Gradient in Species Richness Pattern of Epigaeic Beetles and Underlying Mechanisms at East Slope of Balang Mountain in Southwestern China

“…small mammals in Mt. Qilian in China [57], birds in Himalaya in India [58], fishes, amphibians and reptiles in Hengduan Moutains of Tibetan Plateau in China [59], [60], and plants in Mt. Gaolinggong in south-east Tibet of China [61].…”

Lizard species richness patterns in China and its environmental associations

“…Several previous studies attempted to test these competing hypotheses at different spatial scales using lizard species as model systems. Temperature (Pianka 1967;Scheibe 1987;Fu et al 2007;Powney et al 2010), precipitation (Scheibe 1987) and the number of hours of sunshine (Schall and Pianka1978) have been correlated with lizard species richness, whereas topographic heterogeneity (Owen 1989), actual evapotranspiration (AET) (Powney et al 2010) and potential evapotranspiration (PET) (Fu et al 2007) have been suggested to explain lizard species richness. The driving factors of these results may vary across geographical scale (Powney et al 2010), but increasing studies on other taxa suggest that a series of competing hypotheses or predictors may play different roles to explain species richness variation over broad spatial scales (Costa et al 2007;Gaston 2000;Kerr et al 2001).…”

Can variation in risk of nest predation explain altitudinal migration in tropical birds?

“…Indeed in Costa Rica, the diversity of snakes does not decline until above 800 m and the abundance of all leaf-litter-dwelling herpetofauna may peak at even higher elevations (Scott 1976). Likewise, in other tropical and subtropical regions, the relationship between elevation and both snake diversity (Fu et al 2007) and reptile abundance (Hofer et al 1999) is non-linear. Because some altitudinal migrants leave lowland forests to breed in premontane forests where snakes (including birdeating Pseustes and Spilotes) appear to be just as common as in nearby lowland sites (T. Leenders, personal communication; personal observation) it is unlikely that diVerences in snake abundance can fully explain Skutch's (1985) (Robinson et al 2000).…”