The role of genetic processes in determining where plant species do or do not grow remains largely unexplored, despite the importance of this issue for ecological restoration and for efforts to conserve genetic biodiversity. This study will identify both ecological and genetic factors that can limit the distribution of Lasthenia fremontii, an annual plant restricted to California's endangered vernal pool habitats. The specific objectives of this research are as follows: (1) To identify ecological factors that set current population boundaries for L. fremontii through a transplant experiment. (2) To examine the interacting effects of natural selection, genetic variation and gene flow on the fitness of L. fremontii at different depths in the pools by comparing the success of transplants with controlled genetic backgrounds at different elevations across the vernal pool gradient. (3) To describe patterns of gene flow and genetic differentiation within and among vernal pool populations using neutral DNA variation.
This project strives to incorporate genetic and evolutionary processes into our empirical understanding of the mechanisms that influence the distributions of species. While the effects of natural selection, gene flow, and genetic variation on species range limits have been explored theoretically, empirical studies of these processes are almost entirely lacking. Broader impacts of this study will extend to the conservation of narrowly endemic species, especially those restricted to vernal pool habitats, which are jointly threatened by habitat destruction and biological invasion.
