A case of recent long-distance dispersal in the Piriqueta caroliniana complex.

We investigated restriction fragment length polymorphism (RFLP) variation in the chloroplast DNA regions trnS and trnC in 53 populations of the herbaceous perennial Piriqueta caroliniana complex, encompassing its known North American range. The goals of this study were to expand the geographic range of a previous study and to determine the origin of an apparently anomalous population, which possessed a phenotype that was incongruous with other populations in the region. The phylogeography of these populations was investigated with nested clade analysis of a one-step network phylogeny that was based on the RFLP variation of the chloroplast genome. We found evidence of restricted gene flow and past fragmentation, which is consistent with a previous study on the phylogeography of this species complex. The morphological and genetic profile of the one anomalous population indicates that it recently originated from south Florida. Given the urban location of this geographically disjunct population, it is probable that this is an example of a recent human-mediated long-distance dispersal event.