title: Ecological genetics of range size variation in Boechera spp. (Brassicaceae).
abstract: Many taxonomic groups contain both rare and widespread species, which indicates that range size can evolve quickly. Many studies have compared molecular genetic diversity, plasticity, or phenotypic traits between rare and widespread species; however, a suite of genetic attributes that unites rare species remains elusive. Here, using two rare and two widespread Boechera (Brassicaceae) species, we conduct a simultaneous comparison of quantitative trait diversity, genetic diversity, and population structure among species with highly divergent range sizes. Consistent with previous studies, we do not find strong associations between range size and within-population genetic diversity. In contrast, we find that both the degree of phenotypic plasticity and quantitative trait structure (Q ST) were positively correlated with range size. We also found higher F ST: Q ST ratios in rare species, indicative of either a greater response to stabilizing selection or a lack of additive genetic variation. While widespread species occupy more ecological and climactic space and have diverged at both traits and markers, rare species display constrained levels of population differentiation and phenotypic plasticity. Combined, our results provide evidence for a specialization-generalization trade-off across three orders of magnitude of range size variation in the ecological model genus, Boechera.
authors.affiliation: Graduate Degree Program in Ecology C129 Plant Sciences Colorado State University Fort Collins CO 80523-1177 USA ; Department of Integrative Biology University of Texas 1 University Station, C0930 Austin TX 78712 USA.
authors.forename: John T
authors.identifier: 0000-0002-8938-1166
authors.initials: JT
authors.lastname: Lovell
authors.affiliation: Graduate Degree Program in Ecology C129 Plant Sciences Colorado State University Fort Collins CO 80523-1177 USA.
authors.forename: John K
authors.initials: JK
authors.lastname: McKay
keywords: Diversity; evolutionary potential; growth rate; heterozygosity; phenotypic plasticity