Data from: 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 peripheral elevations. Elevation-driven gene flow (isolation by environment), but not isolation by distance was found across the species range. These findings were the same towards high- and low-elevation range limits and were inconsistent with two common center-edge hypotheses invoked for the formation of species range limits: 1) decreasing habitat quality and population size; 2) swamping gene flow from large, central populations. This pattern demonstrates that climate, but not center-edge dynamics, is an important range-wide factor structuring M. laciniatus populations. To our knowledge this is the first empirical study to relate environmental patterns of gene flow to range limits hypotheses. Similar investigations across a wide variety of taxa and life histories are needed.Marker genotypesGenotypes for 11 codominant markers—including 3 single-copy, nuclear-gene-intron-length markers and eight microsatellite markers described in Sexton et al. for 23 populations of Mimulus laciniatus in the California Sierra Nevada.laciniatus_microsat_dataset_Sexton_4_Dryad.xlsxDistance matricesGenetic, spatial, and climate distances among 23 populations of Mimulus laciniatusdistance_matrices_Sexton_4_Dryad_V2.xlsxPlant density dataAverage plant density sampled in moss patches within 12 randomly assigned 0.5 square meter plots at each Mimulus laciniatus study population.density_dataset_Sexton_4_Dryad_corrected.xls