Fig. 4: Visualization of the fungal fundamental niches and their correlations with functional traits.

a Position of fungal optimal growth within the three-dimensional fundamental niche space. Dots represent individual isolates, shapes reflect phylogenetic placement (round: Ascomycota, square: Basidiomycota, triangle: Mucoromycota, diamond: Mortierellomycota). b Niche breadth of individual fungal isolates in the three-dimensional fundamental niche space. Edge lengths of the boxes correspond to respective niche breadths within each fundamental niche gradient, defined as >25% of maximum growth. Fungal isolates (individual graphs) are sorted by the scores of isolates on RC1 (rotated component 1, Fig. 3b), dark colors correspond to low values (dense mycelial growth), light gray colors to high values (fast mycelial growth). c Direct correlations of RC axes and individual functional traits with niche traits. Dot size and color correspond to correlation coefficients r obtained by Pearson´s or Spearman rank correlations—only significant values are displayed (P < 0.05). Crosses indicate significant predictors for the position of fungal optima within the three-dimensional fundamental niche matrix (permutation multivariate analyses of variances (RC axes) and stepwise model selection based on redundancy analyses (individual functional traits)). Effects of fundamental niche gradients on the relative distribution of RC scores, calculated as arithmetic means of RC scores weighted by the relative abundance of fungal isolates along the fundamental niche gradients of C:N supply (d), temperature (e), and water availability (f) (Fig. S7). Lines represent outputs from generalized additive models. Water potential was modeled only to −1.2 MPa, below this value data were driven by two isolates only. For trait abbreviations see Figs. 1 and 2; niche matrix: optima in the three-dimensional niche matrix; N_opt, temp_opt, water_opt: isolate-specific optima in C:N (N), temperature (temp) and water availability gradients; N_breadth, temp_breadth, water_breadth: isolate-specific niche breadth in respective gradients; niche_cube: three-dimensional niche space for individual isolates (Table S1).