Aim I tested the hypothesis that Uniola paniculata populations are divided into eastern and western lineages, with the southern tip of Florida possibly acting as the primary geographic break, as is the case in co-distributed animal taxa.
Results I found four cpDNA haplotypes and two major lineages: eastern (Atlantic Coast) and western (Gulf Coast). The eastern lineage is ancestral to the western lineage, and the phylogeographic break separating the two occurs at the southern tip of Florida.
Main conclusions The phylogeographic analysis suggests that U. paniculata populations survived the last glacial maximum (LGM) in refugia in southern Florida (including the Keys) and the Bahamas, and possibly in other locations, including Cuba, Texas and the Gulf Coast of Mexico. Following the LGM, a combination of vicariance and dispersal explains the current distribution of haplotypes into an eastern and western lineage. There are seven populations that contain a haplotype that is not in its native range; at least five of these populations are very likely explained by human-mediated transplantation. The phylogeographical pattern observed in U. paniculata is concordant with co-distributed animal taxa that experience a maritime discontinuity at the southern tip of Florida
