Systematics Section / ASPT
Downie, Stephen R. .
Tribe Oenantheae: A contribution to a family-wide phylogenetic classification of Apiaceae.
Previous molecular systematic studies into the higher-level relationships of Apiaceae subfamily Apioideae have revealed a strongly supported clade recognized as tribe Oenantheae Dumort. These plants may have tuberous roots, corky-thickened fruits, highly reduced (rachis) leaves and other adaptations for existence in wet habitats, yet no unique morphological synapomorphy supports their monophyly. Phylogenetic relationships within Apiaceae tribe Oenantheae were investigated using sequence data from the cpDNA psbI-trnK 5’exon and nrDNA ITS regions. The cpDNA region includes four intergenic spacers and the rps16 intron and is approximately four kilobases in size. These five cpDNA loci were analyzed separately and in combination to assess their relative utility for resolving relationships. One hundred and thirty-one accessions were examined, representing all 17 genera recognized in the tribe and approximately one-half of its species. Maximum parsimony analyses of separate cpDNA and ITS data sets yield highly concordant trees. Phylogenies derived from maximum parsimony, Bayesian or maximum likelihood analyses of combined cpDNA and ITS data for 82 accessions are fully resolved, well-supported and consistent with one another. The North American genera Atrema (Bifora pro parte), Cynosciadium, Daucosma, Limnosciadium, Neogoezia, Oxypolis, Ptilimnium and Trepocarpus ally with the western hemispheric and Australasian genus Lilaeopsis in a strongly-supported clade that is sister group to a clade comprising primarily Old World taxa (Afrocarum, Berula, Cryptotaenia, Helosciadium and Sium). Oxypolis and Ptilimnium are not monophyletic, nor are Berula, Bifora, Cryptotaenia and Sium as revealed through previous studies. Cicuta and Oenanthe unite as monophyletic and comprise a sister group to all aforementioned taxa. The North American genus Perideridia is sister group to all other oenanthoid genera. Generic-level studies of Berula, Cicuta, Sium and Perideridia have been completed; revisionary studies of the North American endemic genera Oxypolis, Ptilimnium and Daucosma, and of the widely disjunct genus Lilaeopsis, are currently underway.
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1 - University of Illinois Urbana, Department of Plant Biology, 265 Morrill Hall, 505 South Goodwin Avenue, Urbana, Illinois, 61801-3707, USA
cpDNA trnQ-trnK 5'exon
nrDNA ITS sequences.
Presentation Type: Oral Paper:Papers for Sections
Location: Lake Erie/Hilton
Date: Monday, July 9th, 2007
Time: 1:30 PM