Systematics Section / ASPT
Peirson, J. A. , Reznicek, Anton A. .
Phylogeny and biogeography of Solidago subsection Humiles (Asteraceae): Assessing patterns of disjunction and endemism in eastern North America.
The restriction of endemic vascular plants to edaphically stringent postglacial habitats in the Great Lakes region of North America provides an opportunity to examine both the historical effects of the Pleistocene glaciations (including lineage sorting, genetic drift in glacial refugia, and subsequent postglacial migration) as well as contemporary processes of gene flow and ecological selection on population differentiation and lineage divergence. In the current study, molecular systematic and phylogeographic approaches are being utilized to examine the postglacial history and evolution of endemic members of Solidago subsection Humiles in the Great Lakes region. Subsection Humiles comprises five species: S. arenicola, S. kralii, S. plumosa, S. simplex and S. spathulata. Solidago arenicola, S. kralii, and S. plumosa are restricted to disjunct populations in the southeastern United States. Solidago spathulata and S. simplex subsp. simplex both occur in western North America; the former is confined to coastal dunes from northern California to northern Oregon, while the latter is widespread from Mexico to Alaska. Certain disjunct populations in the northern Great Lakes region and Quebec have also been assigned to S. simplex subsp. simplex. Solidago simplex subsp. randii, with two varieties endemic to the Great Lakes region, is restricted to rocky barrens, riverbanks and shores in eastern North America. A morphology-based phylogenetic framework has previously been hypothesized for members of subsection Humiles, but molecular phylogenetic corroboration is lacking. Our initial work has focused on recovering phylogenetic relationships within subsection Humiles and between subsection Humiles and other Solidago species. Sequence data from several chloroplast intergenic spacers has been generated to produce a preliminary phylogeny. Additional molecular systematic investigations will help recover the potentially complex postglacial and evolutionary history of the S. simplex complex and also shed light on broader topics including vegetation assembly and ecological speciation.
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1 - University of Michigan, Department of Ecology & Evolutionary Biology, Ann Arbor, Michigan, 48109-1048, USA
2 - University of Michigan, University Herbarium, 3600 Varsity Drive, Ann Arbor, Michigan, 48108, USA
Presentation Type: Poster
Location: Salon C, D & E - Gov Ballroom/Hilton
Date: Tuesday, August 16th, 2005
Time: 12:30 PM