Understanding how population dynamics function to define species geographic ranges is crucial to our understanding of species range limits and how populations can be expected to respond to large scale climate change. This project will investigate the population dynamics of a rare plant, Lespedeza leptostachya and a closely related species, Lespedeza capitata. Through a reciprocal sowing experiment, we will be able to compare the variation between the species and the populations from the southern and northern margins of the rare plant's range. These investigations into variation among populations throughout species ranges will test predictions of species responses to climate change, and ultimately, contribute to the mitigation of climate change and the conservation of biodiversity.