Olfelt, Joel , Handzic, Nizar .
A new species of North American Rhodiola (Crassulaceae).
Recent studies of the North American Rhodiola (Crassulaceae) indicate that the group's most widely used taxonomic treatment does not accurately reflect its evolutionary history. This is of especial concern because one of the currently defined taxa, Rhodiola integrifolia ssp. leedyi (Leedy's roseroot) is on the New York and Minnesota endangered, and the U. S. federal threatened species lists. The taxon is described by some authorities as indistinguishable from R. rosea. To more accurately represent the phylogenetic relationships we examined both newly obtained and previously published morphological, molecular, and geographical data. We sequenced the Internal Transcribed Spacer (ITS) regions I and II from 54 individuals representing all of the described North American Rhodiola taxa. Four of the five known Leedy's roseroot populations were each represented by six individuals, and each of the other five described Rhodiola taxa were represented by six individuals. We evaluated the phylogenetic relationships using Maximum Parsimony (MP) analysis. To test the relationships of the North American Rhodiola with their Asian counterparts we used MP analysis on a combined dataset of published ITS sequences from 21 Asian Rhodiola taxa and the newly obtained sequence data. Preliminary analyses of the North American taxa yields a single tree with strong (98%) bootstrap support for Leedy's roseroot as a distinct clade. Four of the North American taxa, including Leedy's roseroot, are in a clade with the eastern Asian species R. algida. The taxon R. rosea, which is native to North America, Asia, and Europe, is more closely related to the Asian Rhodiola taxa R. heterodonta and R. ishidae than to any of the North American Rhodiola species. The molecular, morphological, and geographical data combine to demonstrate that Leedy's roseroot is distinct from R. integrifolia and R. rosea, and should be elevated to species status (R. leedyi). Furthermore two subspecific taxa (subsp. leedyi and subsp. senecana) should be recognized within R. leedyi.
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1 - Northeastern Illinois University, Biology, 5500 North St. Louis Ave, Chicago, IL, 60625, USA
2 - Northwestern University, Physiology, 1918 Sheridan Road, Evanston, Evanston, IL, 60208-4020, USA
Presentation Type: Poster:Posters for Sections
Location: Khorassan Ballroom/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 5:30 PM