Polyploidy promotes divergent evolution across the leaf economics spectrum and plant edaphic niche in the Dianthus broteri complex

The evolution of the leaf economics spectrum (LES) is known to be constrained by genetic relatedness but also promoted at small geographical and phylogenetic scales. In those cases, we hypothesized that polyploidy would play a prominent role as an outstanding source of functional divergence and adaptive potential. We registered leaf-level nutrient, water- and light-economy-related traits from the LES as well as edaphic properties in the four cytotypes of the autopolyploid Dianthus broteri complex (2x, 4x, 6x and 12x). We analysed the effect of ploidy level on the integration of the LES network, checked if concerted evolution occurred between LES and soil niche and tested the influence of phylogeny on the variables. Alternative evolutionary models for both sets of traits were compared. We found higher divergence of polyploids (especially 6x and 12x) compared to diploids in the LES and soil niche, but these traits are not coevolving. 6x and 12x showed opposite ecological strategies regarding resource use and higher uncoupling of the LES network. Early divergence of traits prevailed in both LES and edaphic niche (supported by better fitted evolutionary models with one optimum per cytotype), but post-polyploidization processes played an important role for the photochemical behaviour. Synthesis. Our results indicated shifts in ecological strategies across Dianthus broteri cytotypes and suggested a powerful role of polyploidy in overcoming constraints for the evolution of plant functional traits.