Post Doctoral Associate University of Florida Gainesville, Florida, United States
Abstract: Species distribution and habitat use may be influenced by both abiotic and biotic factors. Yet the roles of abiotic and biotic factors in driving species distributions often remain unclear. Niche theory distinguishes abiotic factors, biotic factors, and issues related to dispersal limitation as providing key constraints on species distribution. It is often argued that abiotic factors drive large-scale variation in species distribution, while biotic and dispersal-related factors operate at finer scales, such that biotic factors may potentially be ignored at large scales (known as the 'Eltonian noise hypothesis'). Nonetheless, it remains unclear the extent to which these factors govern habitat suitability. Abiotic factors such as habitat characteristics are predominantly considered throughout the history in predicting species distribution, while biotic factors such as species interactions are generally used to a lesser degree. At least three reasons contribute to biotic factors being rarely considered. First, it is often assumed that biotic factors only operate at a local extent. Second, direct information on key biotic factors are often not available or vary in a dynamic way over time, making it challenging to incorporate. Third, it can be challenging to incorporate biotic factors into statistical models in a way that can capture species interactions. This becomes particularly challenging when modeling the distribution of cryptic species that are rare and difficult to detect. We used the multispecies occupancy modeling approached to predict snow leopard (Panthera Uncia) distribution using well known abiotic factors as well as incorporating biotic factors including prey availability of the Siberian Ibex (Capra sibirica) and human avoidance. We contrasted models of snow leopard distribution with and without biotic factors. While abiotic factors including elevation, terrain ruggedness and land cover types were important predictors of snow leopard and prey distributions, incorporating biotic factors such as prey interaction and the associated anthropogenic factors substantially improved model fit. Snow leopard and ibex occupancy and habitat use intensity altered with distance to village, hence reinforcing the importance of incorporating both abiotic and biotic factors in predicting species distribution and habitat use.
