Identifying Environmental Refuges ("Coldspots") from Infection by Batrachochytrium Dendrobatidis of Amphibians in Eastern Europe

Amphibians are the most threatened group of vertebrates. While habitat loss poses the greatest threat to amphibians, a spreading fungal disease caused by Batrachochytrium dendrobatidis (Bd) is seriously affecting an increasing number of species. Although Bd is widely prevalent, there are identifiable heterogeneities in the pathogen’s distribution that are linked to environmental parameters. Our objective was to identify conditions that affect the geographic distribution of this pathogen using species distribution models (SDMs), with a special focus on Eastern Europe. SDMs can help identify hotspots for future outbreaks of Bd, but perhaps more importantly identify locations that may be environmental refuges ("coldspots") from infection. In general, climate is considered a major factor driving amphibian disease dynamics, but in particular temperature has received increased attention. Here, 42 environmental raster layers containing data on climate, soil and human impact were used. Mean annual temperature range (or 'continentality') was found to have the strongest constrain on the geographic distribution of this pathogen. Using the partial dependence visualization module in the R package 'embarcadero', a number of corresponding coldspots were identified.