Climate structures genetic variation across a species' elevation range: a test of range limits hypotheses

Gene flow may influence the formation of species range limits, yet little is known about the patterns of gene flow with respect to environmental gradients or proximity to range limits. With rapid environmental change it is especially important to understand patterns of gene flow to inform conservation efforts. Here we investigate the species range of the selfing, annual plant, Mimulus laciniatus, in the California Sierra Nevada. We assessed genetic variation, gene flow, and population abundance across the entire elevation-based climate range. Contrary to expectations, within-population plant density increased towards both climate limits. Mean genetic diversity of edge populations was equivalent to central populations, however all edge populations exhibited less genetic diversity than neighboring interior populations. Genetic differentiation was fairly consistent and moderate among all populations and no directional signals of contemporary gene flow were detected between central and pe...