Climatic and geographic drivers of fern phylogenetic diversity and variability in Central Argentina

Abstract Mountain ecosystems, with their diverse microhabitats and steep elevational gradients, are ideal for studying plant distribution and the processes driving diversification. Owing to the evolutionary history and life cycle, ferns are mainly distributed in mountains and serve as valuable indicators of these patterns. We investigate fern spatial phylogenetics in the mountains of central Argentina to understand how geographic and climatic factors influence species richness, phylogenetic diversity, and phylogenetic variability. We compiled a dataset of 61 native fern species and analysed the spatial distribution of phylogenetic metrics in relation to geographical and climatic variables. Species richness and phylogenetic diversity peaked at mid-high elevations, while phylogenetic variability was high at low and mid-high elevations, suggesting distinct underlying drivers. Phylogenetic diversity was negatively associated with mean annual temperature and showed a unimodal relationship with latitude. Phylogenetic variability also followed a unimodal pattern with latitude and was positively related to elevation. Our results indicate that areas linked to the Andes host high phylogenetic diversity and variability, identifying them as evolutionary hotspots. In addition, distinct patterns in the northeast suggest the presence of species with unique evolutionary histories, highlighting spatial mismatches between richness and evolutionary uniqueness.