Genetic variation among populations of Valeriana ciliata T.&G. (Prairie valerian) in midwestern prairie fens

Prairie fens form islands of glacial remnant habitats throughout the midwest. A number of species are restricted to these unique wetland habitats, including Valeriana ciliata (prairie valerian-Valerianaceae). Genetic variation was studied in the two remaining populations of V. ciliata in Ohio. These southern, edge-of-range populations were compared with genetic variation in four Michigan populations at the middle of this species' range. Allozyme electrophoresis of individuals in populations of this subdioecious species revealed overall levels of genetic diversity (H-es = 0.245) that were higher than expected for an endemic. Though small in size, the two Ohio populations of V. ciliata had intermediate levels of genetic diversity (H-e = 0.224, 0.254) in comparison to the Michigan populations (H-e = 0.054-0.305). Differences between census population size and effective population size, uneven sex ratios, location within the species' range, and variation in habitat quality all contribute to the level of genetic variation recorded among these V. ciliata populations.