Extremely Low Levels of Genetic Variation and Predicted Shifts in Suitable Niche Space for a Geographically Disjunct, Federally Endangered Legume, Leafy Prairie-Clover (Dalea foliosa)

ABSTRACT Taxa with geographically disjunct distributions and that are endemic or narrowly endemic face the real and immediate threat of local extinction because of inbreeding depression, genetic drift, and environmental stochasticity. These threats are amplified by the predicted changes in climate anticipated within the next 50 years, pointing to the increasing need for population genetic data and translocation experiments to track long-term evolutionary potential in rare plant species. In this study, we assessed population genetic structure within and among natural, augmented, and introduced populations of leafy prairie-clover (Dalea foliosa; Fabaceae) in a geographically disjunct region of the species range (i.e., Illinois) and predicted future potential changes in climate within the study region. Using six novel nuclear microsatellite loci to survey nine populations from Illinois and two from Tennessee, we found extremely limited genetic diversity and no structure among populations within Illinois, with greater genetic diversity within and between populations in Tennessee. Using future climate visualizations, we predict the Illinois portion of the species range will be warmer and wetter within the next 50 years, potentially increasing competition for D. foliosa habitat through woody encroachment. When considered together, these concerns point to the need to prioritize actions that will improve our understanding of the implications of translocations across geographically disjunct regions within the species range.