Fig. 3.
Niche displacement between homoploid (solid outline) and heteroploid sites (dashed outline) of western diploids (nhomoploid = 337, nheteroploid = 275), eastern diploids (nheteroploid = 270), tetraploids (nhomoploid = 294, nheteroploid =205) and hexaploids (nhomoploid = 856, nheteroploid = 554) of Senecio carniolicus derived from canonical correspondence analysis. Homoploid sites of eastern diploids were not included due to their low number. Differentiation of niche optima was defined as the Euclidean distance among centroids of ellipses weighted by axis inertia. The correlation circle (r = 1) shows the environmental variables used as constraints in the ordination, i.e. the Landolt indicator values for temperature (T), continentality (K), light (L), soil moisture (F), soil reaction (R), soil nutrient (N), humus content (H), soil aeration (D) and soil moisture variability (W) averaged for all vascular plant species surrounding S. carniolicus individuals. Axes inertias (i.e. eigenvalues of constrained axes) are given in parentheses. Arrows indicate the direction of shifts in niche optima from homoploid to heteroploid sites.