Systematics/Phytogeography / Taxonomie/ Section
Berry, Paul E. , Riina, Ricarda , Morawetz, Jeffery J. , Van Ee, Benjamin , Wurdack, Kenneth .
A global inventory of Euphorbia – second generation of the NSF Planetary Biodiversity Inventory program.
Euphorbia is a varied but monophyletic clade of plants with over 2000 species worldwide, characterized by a cyathial inflorescence. The Euphorbia PBI project aims to provide an overall taxonomic and phylogenetic framework for the genus and is now in its second year. We have been developing the nomenclatural framework using the online database Tolkin, and we are developing a morphological character matrix as the basis of an online Lucid interactive key. Taxonomic work this year will include completion of the Flora of North America treatment and advances in New World Euphorbia. Students are focusing on the phylogeny of particular clades (e.g. Chamaesyce) and evolutionary questions such as multiple origins of succulence. Targeted field work and herbarium studies have increased the taxon sampling for more in-depth phylogenetic analyses. The Berry lab is screening a wide array of species (currently around 300) using ITS and ndhF sequences, to confirm their clade placement and to attain greater resolution within unresolved subclades. Van Ee and Wurdack have screened nine molecular markers from both coding and non-coding portions of the three genomes in a subsample of 60 Euphorbia species and 10 outgroup genera to re-examine the four-clade phylogenetic hypothesis of Steinmann and Porter’s 2002 study. Their results resolve Steinmann’s clades C and D as always sister to each other, but the rooting of Euphorbia remains ambiguous. The root may be along the branch joining clades A + B to C + D, or along the branches leading to clades A or B. The implications of either the putatively plesiomorphic African and Malagasy clade A or the mostly herbaceous and north-temperate subgenus Esula (clade B) being basal in the genus are intriguing. Upcoming work will focus on subgenus Esula and the Old World Euphorbias, where most species occur, and many of the rare and succulent species.
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1 - University of Michigan, EEB Department and Herbarium, 830 N University, Ann Arbor, MI, 48105, USA
2 - University of Michigan, Herbarium, 3600 Varsity Drive, Ann Arbor, Michigan, 48108, USA
3 - University of Michigan, EEB Department and Herbarium, 830 N University Av, Ann Arbor, MI, 48105, USA
4 - Harvard University, OEB Department, 22 Divinity Ave, Cambridge, MA, 02138, USA
5 - Smithsonian Institution, Botany Department, PO Box 37012, NMNH, MRC-166, Washington, DC, 20013-7012, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Wednesday, July 30th, 2008
Time: 2:15 PM