Spatial pattern, ecological niche, and interspecific competition of Viperidae in Korea
Studies on ecological niche of sympatric species have been interesting subjects which focused on the competition between similar species. In particular, the studies may predict spatial distribution of the species and competing areas through species distribution modeling. This study aims to verify the spatial distribution and ecological niches of 3 species, Gloydius ussuriensis, G. brevicausus, G. saxatilis, and, based on the results, to find out the distribution pattern of actually compete among those species. In order to develop species distribution models for the 3 Gloydius species, we applied the Maximum Entropy Approach which used 3 kinds of distribution spots and environmental variables (19 variables of climate, altitude, and habitat).
Since the 19 climate variables showed very high correlations, 4 PCs, which has an eigenvalue of 1 or higher, were extracted, and each PCs showed that it was related to altitude which is a topographical variable. In addition, as a result of the calculation of the value of PI(Pianka Index) and verification the ecological niches of the environmental variables of the 3 species, we could find that the ecological niches of the 3 species significantly overlapped according to the environmental variables. The distribution areas of the prediction models, however, were different from each other, and, compared to the total area of investigation, relatively narrow area was found to have competition among species. Although we could not find the direct cause of the difference in spatial distribution of the 3 Gloydius species, it is expected that the causes of different spatial distribution among the species will be found if future studies are carried out for topographical variables (e.g. slope, aspect, microhabitat, soil, solar radiation) and other various variables (e.g. home range, food, reproductive strategies) in the competition area shared by the Gloydius.