Abstract Detail

Systematics Section/ASPT

Freyman, William A. [1], Olfelt, Joel [2].

Phylogeny and divergence times among the North American Rhodiola (Crassulaceae) species.

Plants in the genus Rhodiola (Crassulaceae) are perennial herbs that generally grow in alpine and arctic regions of Eurasia and North America. Some are used in traditional medicines, and some, such as the North American Rhodiola integrifolia ssp. leedyi, (Leedy’s roseroot) are rare and narrowly endemic. Recent studies that were called for by the U.S. Fish and Wildlife Service suggest that the most widely used taxonomic treatment does not accurately reflect the group’s evolutionary history. To test the relationships of the North American Rhodiola taxa we analyzed the nucleotide sequences of the nuclear ribosomal internal transcribed spacer (ITS) and three non-coding plastid loci: the trnS-trnG intergenic spacer, the trnL intron and adjacent trnL-trnF spacer. We sequenced these regions in over 60 individuals representing range-wide geographic sampling of the six named North American Rhodiola taxa. Combining our data with GenBank sequences from Asian Rhodiola, we performed a phylogenetic analysis using parsimony, maximum likelihood and Bayesian methods. The nuclear and chloroplast tree topologies were largely congruent so the concatenated data matrix 2330 characters long yielded a well-resolved phylogeny. Additionally, we estimated the divergence times of Rhodiola based on the ITS data using a Bayesian relaxed clock model. Our analyses reveal that two separate lineages of Rhodiola colonized North America an estimated 2.0 and 0.7 mya, and that two well-supported clades within R. integrifolia diverged from each other an estimated 1.0 mya. These results suggest that glacial movements during the Pleistocene resulted in allopatric speciation and that the lineage currently classified as R. integrifolia needs revision. Furthermore, a South Dakota population previously identified as R. integrifolia ssp. integrifolia actually belongs in R. integrifolia ssp. leedyi, so we recommend that the conservation measures in place for Leedy’s roseroot populations be extended to the South Dakota population.

Broader Impacts:

1 - Northeastern Illinois University, Biology, 5500 N St Louis Ave, Chicago, IL, 60625, USA
2 - Northeastern Illinois University, 5500 North St. Louis Avenue, Chicago, IL, 60625, USA

Keywords:
Rhodiola
Crassulaceae
phylogeny.

Presentation Type: Oral Paper:Papers for Sections
Session: 37
Location: Belle-Chasse/Riverside Hilton
Date: Wednesday, July 31st, 2013
Time: 10:30 AM
Number: 37008
Abstract ID:714
Candidate for Awards:None