Geographic patterns and environmental drivers of flower and leaf variation in an endemic legume of Southern Patagonia

Abstract

Background: In widely distributed species, geographic patterns of phenotypic variation can appear in a clinal (linear or central–marginal) or mosaic fashion in response to environmental factors. Aim: We assessed spatial patterns and possible abiotic drivers of flower and leaf variation in Anarthrophyllum desideratum, an endemic legume found throughout a wide environmental gradient in southern Patagonia. Methods: We measured 10 floral and foliar traits from 26 populations, distributed along the entire range of the species. We examined phenotypic variation within and among populations, geographical patterns, relationships with climatic and edaphic factors and spatial covariation between flowers and leaves, using uni- and multivariate analyses. Results: Most of the studied traits showed higher variability among than within populations. Within-population variability was not associated with population size. Phenotypic differences among populations were structured by geographic distances. Clinal variation patterns, mainly central–marginal, were detected along a south-west to north-east gradient. Flower and leaf size co-varied across populations, whereas, overall phenotypes were weakly coupled. Phenotypic variation was associated with temperature and soil potassium content. Conclusions: Our results support geographically structured patterns of phenotypic variation and suggest that the abiotic environment has an important role in shaping floral and foliar differences among A. desideratum populations. Non-stochastic processes may account for the geographical variation found in this species.