Amphibian diversity in Himalayas and adaptation to the environments

Amphibians are interesting group of animals that serve as the intermediate members in many food chain and ecological systems. Often referred to as an ‘early warning system’, they are good indicators of environmental health. They are very sensitive to changes in temperature, humidity, and water quality. Their limited dispersal capacity and shorter breeding season make them more vulnerable and susceptible to the change.
 
Long-term monitoring of Amphibians in Sun Kosi and Arun region in Nepal and China is undergoing. Detailed inventory of species in the monitoring sites are under preparation. Various methods such as Visual encounter survey, Straight-line Drift Fences and Pitfall Traps are being used to calculate species richness, relative abundance and species activity patterns. Phylogenetic studies are being conducted to understand the amphibian species differentiation, evolutionary patterns and distribution across the Himalayas.
 
There are about 88 species of amphibians belonging to 29 genera in the Himalayas. Of the 88, about 51 species are found in Nepal, about 34 in Bhutan, and about 50 across the Tibetan highlands in China. About 20 species are common to both Nepal and China, six of which are high altitude species found along 3000-5000m altitudes. Similarity on species distribution suggests that Nepal and India are closer than to Bhutan and China. The presentation gives an interesting example of species differentiation of spiny frogs. Figure 1 reflects on the similarity on species distribution among the different nations in the Himalayas.

 

Figure 1. Similarity on species distribution among different areas in the Himalayas

 

Climate change has implications on the species differentiation of amphibians. A species which is restricted to a narrow altitudinal zone migrates to higher altitudes if the climate warms up. Depending on local conditions, it breaks up into smaller units and may remain separated for a different length of time. Under such isolation, if evolutionary conditions become favourable, it might trigger the formation of new species. In amphibians, a change in the precipitation regime can have the same effect. A decrease of moisture in lower zones or in the rain shadow can break up the species range into small isolates in which favourable climate conditions persist. A reverse of the climatic change allows a return to lower altitudes. New contact between the formerly separated units might show different results depending on their degree of genetic divergence and the evolutions of isolating mechanisms. According to Inger (1999), the altitudinal oscillations of the climatic zones in the Himalayas are estimated at a maximum of about 500m.

For further details about the monitoring study on Amphibian diversity in the Himalayas, please contact: Dr. Jiang Jiangping <jiangjp@cib.ac.cn>