Systematics/Phytogeography / Taxonomie/ Section
Kempton, Elizabeth , Columbus, J. Travis .
Phylogenetics, character evolution and diversification of the Eriogonum clade (Polygonaceae).
The Eriogonum clade (Polygonaceae) comprises ca. 325 New World species of North and South American distribution. Formerly this clade was treated as Eriogonoideae (Reveal 2005, Fl. N. Amer. 5: 218-478) but the subfamily has recently been expanded to include a number of additional lineages (Sanchez & Kron 2008, Sys. Bot. 33: 87-96). Nonetheless, multiple phylogenetic studies have found the Eriogonum clade to be monophyletic with strong support. The clade is distinguished from other members of the Polygonaceae by the presence of an involucre (except Gilmania), and the absence of an ocrea (stipular sheath, possibly vestigial in perennial Chorizanthe). This clade includes at least 20 genera; the largest of these are Eriogonum (250+ spp.) and Chorizanthe (50), and the remaining are much smaller (1-3 spp. each). Species within the clade are morphologically and ecologically diverse, and a large number of these are narrow endemics, rare, or of conservation concern. Several authors have speculated that many lineages may have undergone fairly recent adaptive radiation and a variety of factors may have contributed to the diversification of taxa (e.g., geography, edaphism, morphology). My work examines both the taxonomy and evolution of the clade. Several optimality criteria will be used to assess the phylogeny of the group, but here I propose possible taxonomic solutions in light of a Bayesian phylogeny. Using parsimony and Bayesian reconstruction methods I examine the evolution of a number of morphological characters (e.g., presence of awns, lifeform, habit). Also, Geographic Information Systems (GIS) is employed in order to assess the patterns of biogeographical, ecological, and morphological diversification of lineages.
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1 - Rancho Santa Ana Botanic Garden, 1500 N. College Ave, Claremont, CA, 91711, USA
Eriogonum and allies
Geographic Information Systems.
Presentation Type: Oral Paper:Papers for Sections
Location: Room 1/Woodward
Date: Monday, July 28th, 2008
Time: 8:45 AM