Fehlberg, Shannon D. , Ranker, Tom A. .
Phylogeography of Encelia farinosa (Asteraceae) from the Sonoran, Mojave, and Peninsular Deserts.
PLEISTOCENE glaciations have had a profound influence on the genetic structure of plant species throughout the Northern Hemisphere because of range contractions, fragmentations, and expansions associated with climatic fluctuations. Phylogeographic studies have contributed to our knowledge of this influence in several geographic regions of North America, however, very few phylogeographic studies have examined plant species in the Sonoran, Mojave, and Peninsular deserts. In this study, we used sequence data from the chloroplast DNA psbA-trnH intergenic spacer to obtain information on phylogeographic patterns among 310 individuals from 21 populations of Encelia farinosa (brittlebush; Asteraceae) across its range. We applied several phylogenetic, population, and spatial genetic analyses that allowed us to interpret our data with respect to Pleistocene glaciation. These analyses indicate that the distribution of genetic variation in E. farinosa is independent of varietal designations and historical vicariance events. Instead, E. farinosa displays patterns of genetic differentiation and geographic structuring consistent with postglacial colonization from multiple refugia. Encelia farinosa is characterized by distinct haplotype lineages significantly associated with geography. Centers of diversity for the species occur in southwestern Arizona, the plains of eastern Sonora, and southern Baja, all of which are putative sites of glacial refugia as predicted by analyses of macrofossil and pollen data. Nested clade analysis suggests that genetic structure in E. farinosa has been affected by past fragmentation followed by range expansion. Range expansion in several locations is further supported by significant departures from neutrality for values of Fuís F and Tajimaís D, and mismatch analyses.
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1 - University of Colorado, Department of Ecology and Evolutionary Biology, UCB 334, Boulder, Colorado, 80309, USA
2 - University of Colorado, University Museum & Department of Ecology and Evolutionary Biology, 265 UCB, Boulder, Colorado, 80309, USA
nested clade analysis
Presentation Type: Oral Paper:Papers for Topics
Date: Monday, July 31st, 2006
Time: 8:45 AM