Systematics Section / ASPT
Givnish, Thomas J. , Van Ee, Benjamin , Skinner, Mark W. .
Phylogeny, floral evolution, and biogeography in North American Lilium (Liliaceae).
The 21 species of Lilium endemic to eastern and western North America have undergone extensive radiation in floral form and habitat. To evaluate relationships among these and other lilies worldwide, we sequenced matK, ndhF, rpl16, rbcL-accD, and trnL-trnF from the plastid genome and nrDNA ITS for all North American taxa, 15 Eurasian lilies, and outgroups in Fritillaria, Cardiocrinum, and Notholirion. A combined analysis indicates that the North American taxa represent two independent invasions from Eurasia, including two eastern species with upright flowers (Lilium catesbaei, L. philadelphicum) and 19 species from eastern and western North America with pendent/horizontal flowers. Within the latter core group, there are three reasonably well-defined clades, including (a) seven species from eastern North America; (b) a Klamath clade of seven species centered in the Siskiyous and nearby coast; and (c) a Sierra clade of five species. Most members of the Klamath clade share a terminal constriction of the smaller metacentric chromosome, unique among lilies worldwide; all but one species occurs on dry ground, in contrast to the mostly wet-ground Sierran species. Molecular data largely support Skinnerís recognition of two principal clades in eastern North America, including three northern/Appalachian species with red styles and yellow bulbs and three southern/Coastal Plain species with ridged sepals. Lilium michauxii is sister to these clades in the combined analysis, and closely resembles several western taxa morphologically. Hybridization has clearly played an important role, with a number of conflicts between the plastid and nuclear phylogenies. Hummingbird pollination appears to have arisen at least six times, in association with cool conditions at higher elevations or with cold, foggy conditions near the Pacific in nw California; moth pollination appears to have evolved three times from ancestral butterfly pollination. Dry-ground species generally have compact bulbs with folded bulb-scales; wet-ground species have more elongate bulbs/rhizomes.
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1 - University of Wisconsin Madison, Department of Botany, Birge Hall, 430 Lincoln Drive, Madison, Wisconsin, 53706-1381, USA
2 - Smithsonian Institution, Botany, Washington, D.C., 20560, USA
3 - USDA NRCS National Plant Data Center, P.O. Box 74490, Baton Rouge, Louisiana, 70874-4490, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Continental A/Hilton
Date: Tuesday, July 10th, 2007
Time: 10:45 AM