Species Richness Patterns and Morphological variations in Anurans Along an Elevational Gradient of Annapurna Conservation Area, Nepal

Abstract

Anurans are a group of amphibians widely distributed worldwide. Body size and extremities of amphibians along an elevational gradient have always been a subject of curiosity. To study the species richness and morphological variation of anurans live samples were measured. An intensive field survey was conducted in August 2022, from Phedi (1150 m) to Mardi (4000 m) following the trekking trail. The amphibian survey was done by using the nocturnal time-constrained visual encounter method along the transects (100m × 4m). The survey was conducted between 7:00 p.m. and 9:00 p.m. Different morphological variables were measured by vernier caliper and environmental variables such as elevation were measured by using GPS. However, QGIS extracted slope, aspect, and TRI from DEM and NDVI from satellite images. Linear regression showed the decline of species richness as elevation increases. Similarly, linear regression showed that the body size of anurans increases as elevation increases i.e., it follows Bergmann’s rule. However, multiple linear regression showed that the length of the metatarsus of the family Bufonidae decreases as elevation increases i.e., it follows Allen’s rule but extremities of family Dicroglossidae does not follow. Hierarchical partitioning showed that temperature and NDVI were the predictors that influence species richness, body size and extremities of anurans.