Systematics/Phytogeography / Taxonomie/ Section
Wheeler, Erica J , Mcneal, Dale , Pires, J. Chris .
Systematics and phylogeography of the genus Allium in North America.
The genus Allium is widespread in temperate regions of the northern hemisphere and is especially diverse in the warm, dry climates of the Mediterranean basin and central Asia. Most of the species endemic to North America belong to the trans-Atlantic subgenus Amerallium which covers most of the continent south of the 52nd parallel. Phylogenetic evidence supports the monophyly of these New World species, presenting an opportunity to test continent-level phylogeographic hypotheses and to assess the validity of taxonomic groups with molecular phylogenetic methods. Our analysis identifies two main evolutionary lineages in North America that are separated by the Rocky Mountains but overlap geographically to some degree. One lineage is most diverse in the west, is relatively species-rich and includes species with cellular-reticulate bulb coats. The other lineage is most diverse in the east, is relatively species-poor and includes species with fibrous-reticulate bulb coats and with iris-like rhizomes. Future work will focus on testing for climatic and edaphic correlates of genetic divergence to identify factors that may have driven speciation in the genus Allium in North America. Eight informal taxonomic alliances based on morphology and anatomy, are largely supported by the molecular data confirming the validity of the combination of characters used to circumscribe each of these groups (bulb morphology, bulb coat, leaf number, leaf shape, ovarian crests). Some alliances however, are not strictly monophyletic based on our data, and future work will focus on clarifying the evolutionary relationships among these species.
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1 - University of Missouri, Biological Sciences, 1201 East Rollins Road, 311 Christopher S Bond Life Sciences Center, Columbia, Missouri, 65211, USA
2 - University of The Pacific, Department of Biological Sciences, 3601 Pacific Avenue, Stockton, California, 95211-0197, USA
3 - University of Missouri, Biological Sciences, 1201 East Rollins Road, 311 Life Sciences Center, Columbia, MO, 65211, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, July 29th, 2008
Time: 2:15 PM