Wallace, Lisa , Wheeler, Gregory , Mcglaughlin, Mitchell , Helenurm, Kaius .
Utility of deep population sampling and a single locus to reconstruct a species phylogeny of Acmispon subgroup Syrmatium (Fabaceae).
Species tree methods of phylogenetic reconstruction have the ability to account for the stochastic nature of gene genealogies through the coalescent model, but it can be difficult to determine whether sampling a greater number of individuals or loci will result in increased accuracy of the resulting phylogeny. Several studies have shown that adding more individuals is most effective for phylogeny reconstruction in groups of recently diverged taxa and when the time between speciation events is short. In this study, the utility of deep population sampling and a single locus to reconstruct phylogenetic relationships within Acmispon subgroup Syrmatium (Fabaceae) was explored. Species comprising the Syrmatium group are restricted to the western U.S.; many are endemic to California. Genetic data have indicated monophyly of Syrmatium, and several morphological characters are synapomorphic for the group. However, evolutionary patterns among species within Syrmatium remain largely unknown. Sequence data at three chloroplast regions (ndhA intron, psbD-trnT spacer, rpl16 intron) were collected from more than 450 individuals sampled from multiple populations of 10 of the 11 species of Syrmatium. Gene tree/species tree methods were used to reconstruct a species phylogeny, with an emphasis on establishing the most likely progenitors of A. argophyllus and A. dendroideus, which have diversified on the California Channel Islands. Among 480 sequences examined, 165 unique multilocus haplotypes were identified. Gene trees suggest the presence of extensive ancestral polymorphism, which is not unexpected in recently diverging systems. The island species, A. argophyllus and A. dendroideus, are not sister species, and varieties of these two species are not monophyletic. Notably, A. argophyllus var. niveus, the only variety of this species to occur on the northern islands,contains strongly divergent haplotypes that are unlike others found in A. argophyllus. The resulting framework of evolutionary relationships within Syrmatium will enhance our ability to understand morphological transitions, evaluate intraspecific taxonomy, assess conservation risks, and test hypotheses concerning the evolution of the endemic Acmispon taxa on the Channel Islands.
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1 - Mississippi State University, PO Box GY, Mississippi State, MS, 39762, USA
2 - University Of Northern Colorado, 501 20th St, Box 92, Greeley, CO, 80639, USA
3 - University Of South Dakota, Department Of Biology, Vermillion, SD, 57069, USA
California Channel Islands.
Presentation Type: Oral Paper:Papers for Sections
Location: Delaware D/Hyatt
Date: Wednesday, July 11th, 2012
Time: 8:30 AM