Chloroplast DNA diversity in Packera (asteraceae) : a phylogeographic study of Packera contermina and three related species from southwestern Alberta based on chloroplast DNA variation

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Golden, Joanne L.
University of Lethbridge. Faculty of Arts and Science
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Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 1999
Members of the genus Packera (Asteraceae) are widespread in North America, but most are found in western regions of the continent where extensive morphological integradation is common. Previous molecular systematic studies found that four species in southwestern Alberta, a region proposed to be at the interface of the Cordilleran and Laurentide ice sheets during the last advance of Pleistocene glaciation, showed unusually high levels of inter- and intrapopulational chloroplast DNA variation. The present study analyzed chloroplast haplotype phylogeny, frequency variation, and geographic distribution patterns in Packera contermina and closely related species P. pseudaurea, P. cana, and P. cymbalarioides from southwestern Alberta, nothern Montana, and northwestern Wyoming. Restriction site analyses of chloroplast DNA from 730 individuals across 34 populations of the four species revealed fifteen haplotypes, of which seven are commonly found in other North American Packera species. Three haplotypes were detected in P. cymbalarioides, seven in P. cana, eight in P. pseudaura, and twelve in P. contermina. The level of ahplotype frequency variation among populations was high in P. cymbalarioides (0=I) moderate to low in P. contermina (0=0.333) and P.cana (0=0.261), and very low in P.pseudaurea (0=0.085), possibly reflecting differences in the species' history. Phylogenetic analyses revealed 2 groups of haplotypes, one of which is found mainly in populations from the Great Basin of North America and the second in populations of more coastal and northern regions. The presence of haplotypes from both groups of Packera species suggests that the cpDNA diversity in southern Alberta arisen through hybridization/introgression events that have involved a number of species from outside of the region.
x, 81 leaves : ill., maps ; 28 cm.
Dissertations, Academic , Compositae -- Geographical distribution , Chloroplasts -- Formation , DNA