Systematics/Phytogeography / Taxonomie/ Section
Danderson, Clark A. , Hermann, Michael , Downie, Stephen R. .
Resolving phylogenetic relationships within the Arracacia clade (Apiaceae subfamily Apioideae) using ITS and cpDNA sequence data.
Previous molecular systematic studies into the higher-level relationships of Apiaceae subfamily Apioideae have revealed a well-supported clade comprising a morphologically heterogeneous assemblage of ten genera (Arracacia, Coaxana, Coulterophytum, Dahliaphyllum, Donnellsmithia, Enantiophylla, Mathiasella, Myrrhidendron, Prionosciadium and Rhodosciadium). This clade is named after its largest and earliest described genus, Arracacia (Downie et al. 2000, 2001). No obvious morphological synapomorphies are known for the group, although many genera are characterized by polyploid members, the presence of petals with inflexed apices and a distribution in high montane temperate or sub-alpine habitats of meso- and South America. Problematic to this group is that previous efforts to delimit the genus Arracacia to the exclusion of other genera have been unsuccessful, resulting in a taxonomy best described as provisional. In an effort to resolve phylogenetic relationships within the Arracacia clade and to delimit monophyletic genera, we are examining nrDNA ITS and cpDNA sequences. Our results to date, based on maximum parsimony analysis of ITS sequences from 142 accessions, show that Arracacia, Prionosciadium, and Rhososciadium are each highly polyphyletic. In fact, all genera other than Myrrhidendron and the monotypic Mathiasella are not monophyletic based on these initial results. Recent additions to the Arracacia clade include the Central and South American genera Neonelsonia and Ottoa. The genera Niphogeton, Perissocoeleum and Cotopaxia comprise a weakly supported sister group to the Arracacia clade or constitute its most early diverging lineages. To further resolve relationships and ultimately, to revise the taxonomy of the group, additional DNA sequence data are needed. Therefore, we also present results of a pilot study that examines 18 non-coding cpDNA loci from the chloroplast genome and determines their efficacy in resolving inter- and infrageneric relationships within the Arracacia clade.
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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
2 - Bioversity International, Cali, Colombia
Presentation Type: Poster:Posters for Sections
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM