Drummond, Christopher .
Diversification of Lupinus (Leguminosae) in the western New World: Derived evolution of perennial life history and colonization of montane habitats.
Previous phylogenetic studies of Lupinus (Leguminosae) based on nucDNA loci (ITS1+2, LEGCYC1A, LEGCYC1B) have shown that the western New World taxa form a monophyletic group comprising the majority of species in the genus. Molecular dating of nucDNA has provided further evidence that within this western New World clade,a derived lineage of western South American species experienced high rates of diversification following final uplift of the Andes Mountains 2-4 million years ago (mya). For this study, three cpDNA regions (trnL, trnS–trnG, trnT–trnL) were examined to estimate the timing and rates of diversification among the western New World species of Lupinus. The branching order among Old World and New World species is poorly resolved, consistent with a complex early period of geographic dispersal following divergence from the most recent common ancestor of the genus (6.9 Â± 1.0 mya), whereas the western New World lineages (6.3 Â± 1.1 mya) are recovered as monophyletic. This western New World clade consists of a basally branching assemblage of annual plants endemic to the lower elevations of western North America, from which two species–rich groups are derived: the monophyletic western North American perennials from the Rocky Mountains and Pacific slope (1.3 Â± 0.3 mya, 2.6-4.1 spp./my), and the predominantly perennial species from the Andes and highlands of Mexico (1.5 Â± 0.6 mya, 2.3-5.3 spp./my). These results suggest that rapid diversification of Lupinus in the western New World may not be restricted to the Andes, while comparative analyses of life history and maximum elevation indicate that the derived evolution of perennial life history is correlated with a transition to montane habitats.
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1 - University of Idaho, Department of Fish and Wildlife Resources, P.O. Box 441141, Moscow, ID, 83844-1141, United States
Presentation Type: Oral Paper:Papers for Topics
Location: Boulevard B/Hilton
Date: Monday, July 9th, 2007
Time: 10:45 AM