Jabbour, Florian , Rojas, Alfonso , Renner, Susanne .
A phylogeny of the Delphinieae (Ranunculaceae) reveals that Aconitum is embedded in Delphinium: Implications for flower evolution.
The Delphinieae comprise the mostly holarctic genera Aconitum L. and Delphinium L., with c. 350 species each, and the small Consolida and Aconitella, which recent work has shown to be part of Delphinium (Jabbour and Renner, in review). Monkshoods and larkspurs have complex bee-adapted flowers, with bisymmetry (creating bee working platforms), hidden nectar, a petaloid outermost whorl of tepals, and a reduced innermost one. A characteristic feature of Delphinieae flowers is the presence of nectar-leaves nested inside the dorsal tepal (either hooded or spurred) of the outermost flower whorl. The mutual monophyly of Aconitum and Delphinium has long gone unquestioned, but extensive species sampling (using plastid and nuclear DNA sequences) reveals that Aconitum is embedded in Delphinium. Delphinium subgenus Staphisagria, with three species endemic to Mediterranean islands, is sister to all remaining Delphinieae. Using a Bayesian relaxed molecular clock and maximum likelihood ancestral area reconstruction we inferred the migration routes and times of the Delphinieae expansion to the Mediterranean, tropical African mountains (a single event c. 12.9 Mya), and North America. Since the sister clade of the Delphinieae is uncertain, the region of origin cannot be inferred; the eastern Himalaya and southwestern China are richest in endemic species. The newly revealed relationships imply an evolutionary increase in spur length and homoplastic reduction in the innermost tepal whorl. The synorganization of nectar-leaves evolved once in the ancestor of the most derived lineage, Aconitella/Consolida. To achieve monophyletic genera in the Delphinieae one could resurrect Staphisagria J. Hill (1756) and transfer the 52 species of Aconitella and Delphinium, which would involve only seven name changes because most were placed in Delphinium at some time. Developmental genetic studies of flower evolution in the Delphinieae will benefit from the new phylogeny.
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1 - Systematic Botany and Mycology, Department of Biology, University of Munich (LMU), Munich, 80638, Germany
Presentation Type: Oral Paper:Papers for Sections
Location: Lindell B/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 10:45 AM