Fig. 1

Distribution of Bd and Bsal and niche overlap analysis. Localities positive for Bd (green dots) and Bsal (red dots) on a background of altitudinal gradients are shown in a. The contributions of environmental variables to the first two PC axes are presented in b (standard definitions for each variable provided in Additional file 1: Table S1). A visualization of occupied and available niche space for the two pathogens is provided in c, based on the first two axes of a principal component analysis. Solid and dashed contour lines represent 100% and 50% of the available environment in Eurasia, respectively. The green, red and blue filled areas indicate the occupied niches of Bd, Bsal and overlap, respectively, with deeper colors representing higher overlap. Histograms d-e display the expected distribution of Schoener's D index values for the niche equivalence and niche similarity tests, with red diamonds indicating the actual observed niche overlap