A preliminary phytogeographical analysis of inter- and intra-populational chloroplast DNA variation in Packera pseudaurea (Asteraceae : Senecioneae) from southwestern Alberta and adjacent Montana

Packera pseudaurea (Rydb.) Weber & Love has previously been identified as a species containing an unusually high level of chloroplast DNA (cpDNA) poly morphism. Proposed sources of this intrapopulational variation have include d hybridization and introgression, either ongoing or resulting from migrati ons associated with past glacial events. Restriction site analysis was perf ormed on individuals from seven populations of P. pseudaurea from southern Alberta and adjacent Montana to assess variation more precisely. High level s of intrapopulational polymorphisms comprising a total of nine different h aplotypes, only one apparently unique to the species, were detected in all but one southern population. The haplotypes separate into two groups upon p hylogenetic analysis, a separation that corresponds to that detected in a w ider sampling of Packera species. With one or two exceptions, the haplotype s of one group are also found in species based west of the Rocky Mountains. Those of the other are found in species based all over North America. Thes e results lend support to the hypothesis that the variation in P. pseudaure a originated when the ranges of different Packera species were brought toge ther by glaciation.