Systematics Section / ASPT
Wallace, Lisa , Jacobs, Bridget , Walsh, Robert , Nepokroeff, Molly .
Using nucleotide sequences from nuclear (Nitrate Reductase) and chloroplast (trnC-trnD) introns for phylogenetic reconstruction of closely related species: An example in Hawaiian Schiedea (Caryophyllaceae).
The Hawaiian plant genus, Schiedea (Caryophyllaceae), exhibits shifts from wet or mesic forest habitat and hermaphroditic breeding system into more open, drier, windswept, cliff and coastal habitats that appear to be accompanied by shifts to dimorphic breeding systems. In order to examine evolutionary transitions in habitat and breeding system, a robust phylogenetic framework is critical, but previous efforts at phylogenetic reconstruction have been confounded by a lack of variation in genes (ITS and ETS) typically useful at lower taxonomic levels in plants. In the present study, we explore the utility of nucleotide sequences from introns in the chloroplast (trnC-trnD) and nuclear (nitrate reductase intron #3) genomes to resolve phylogenetic relationships within Schiedea. Little variation at nucleotide sites or indels was observed among Schiedea species for the trnC-trnD region (0-2 % raw sequence divergence). By contrast, the NIA intron exhibited substantially greater levels of phylogenetically-informative variation at sites and indels. Additionally, low levels of divergence were detected among NIA clones within most of the species, suggesting the presence of multiple loci or multiple alleles associated with a single locus. In comparison to previous phylogenetic hypotheses based on ITS, ETS, and morphology, the results from this study show many points of concordance to these other gene phylogenies. The combination of the four molecular data sets with morphological characters results in a better resolved phylogeny that will be useful for testing hypotheses on the evolutionary transitions in habitat and breeding system that have occurred in this genus.
1 - University of South Dakota, Department of Biology, 414 East Clark Street, Vermillion, South Dakota, 57069, USa
Presentation Type: Poster
Location: Special Event Center (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 12:30 PM