FIGURE 5 Distance decay of community similarity across the Quercus alnifolia (Qa) habitat. Distances among Qa sampling sites were calculated either based on the isolation-by-resistance (IBR) scenario reflecting the spatial distribution of Qa forest patches (FRAIBR, left panel) or on the topoclimatic distances among sampling sites (ENVPC1-2, right panel). Community similarity was estimated using the Simpson similarity index (1 - βSIM) at ASV (filled circles, solid regression line) and OTU (open circles, dashed regression line) levels. For display purposes, the decay curves were fitted using generalized linear models (GLMs) with a negative exponential function. Regression slopes, coefficients of determination (pseudo-R 2) and p-values are provided on the top of each panel. See Table 3 for multivariate matrix regression analyses assessing the independent contribution of each predictor to community dissimilarity.