Molecular Ecology and Evolution
Wheeler, Gregory L , McGlaughlin, Mitchell E , Helenurm, Kaius , Wallace, Lisa .
A comparison of nucleotide and microsatellite diversity for understanding intraspecific evolutionary patterns in two California-endemic Lotus species.
The Channel Islands, an archipelago of eight oceanic islands off the coast of California, comprise a geographically unique system with a high level of plant endemism. It is not known whether the plant taxa found on the Islands are relicts of species that once existed throughout mainland California and the Channel Islands or if the unique taxa evolved into new niches on the islands. To address this question, it is necessary to have an understanding of phylogenetic relationships within species on the islands and between island and mainland species. In this study, we examined phylogenetic relationships in Lotus dendroideus, an endemic species, and L. argophyllus, a species with both island-endemic and mainland varieties, using DNA sequences from three chloroplast regions and genotypic data from seven chloroplast microsatellite loci. We compared the information content of these two data sets for reconstructing intraspecific evolutionary patterns, and tested the hypothesis that the microsatellites would provide more phylogenetically informative characters relative to effort compared to DNA sequencing without an increase in homoplasy. Additionally, we used the combined data set to evaluate intraspecific taxonomy for both species and to identify the most genetically similar mainland species. While the microsatellite loci assayed through fragment-based genotyping methods did provide additional phylogenetic characters with less effort than DNA sequencing, length variation in these loci did not always correspond to variation in the repeat region. Thus, care must be taken to ensure homology of fragment sizes when using the information at microsatellite loci for phylogenetic inference. Neither data set provided strong support for all of the morphologically-determined varieties in either species. Additionally, neither island species was monophyletic relative to mainland relatives. These findings suggest the retention of ancestral polymorphism throughout these taxa, which could make reconstructing a maternal phylogeny difficult. Nevertheless, these data do allow for robust estimation of population-specific patterns within the islands.
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1 - Mississippi State University, Biological Sciences, 295 Lee Blvd, Mississippi State, MS, 38762, USA
2 - University of Northern Colorado, Biological Sciences, 501 20th Street, Ross Hall 1560, Greeley, CO, 80639, USA
3 - University Of South Dakota, Department Of Biology, Vermillion, SD, 57069, USA
California Channel Islands
Presentation Type: Poster:Posters for Topics
Location: Khorassan Ballroom/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 5:30 PM