Seven populations of the federally-listed threatened Pitcher's thistle (Cirsium pitcheri), a rare plant restricted to the shorelines of the western Great Lakes, are being assessed for long-term population viability. Our research brings together a long-term demographic data set, repeated molecular genetic sampling and an assessment of quantitative trait variation to assess population viability and extinction risk of natural and restored plant populations. The fundamental questions addressed in this project are: (1) Does population viability analysis accurately predict population trends and extinction probabilities; and (2) Do restored populations follow a similar evolutionary trajectory as natural populations, i.e. do demographic and genetic parameters differ between restored and natural populations? Support from NSF will continue long-term data collection and expand modeling to integrate demographic and genetic variation of multiple restored and natural populations of C. pitcheri. This will greatly improve the robustness and applicability of our research toward understanding how long-term demographic variability affects population viability, as well as enhance restoration and management of this threatened species. Despite the need for long-term demographic data and repeated genetic analysis to accurately model population viability, few such data sets exist, and ours represents a unique combination for restored and natural populations of a threatened species. Our work also meets federal recovery planning objectives for research and restoration of this species.
