Dissertations and Theses @ UNI
Availability
Open Access Thesis
Keywords
Cruciferae--Phylogeny; Cruciferae; Academic theses;
Abstract
The taxonomy of Physaria has continually been in a state of flux, especially certain groups of species within the genus. The Physaria reediana species complex (sensu Rollins) is an example of one of these problematic groups. The systematics of the Physaria reediana species complex was examined by a combination of techniques. A Bayesian analysis of 71 aligned sequences of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA (nrDNA) provided a fairly well-supported phylogeny (mean posterior probability per node: 0.5429) of a portion of the genus, which included the. species in the complex. Recent nodes showed the highest statistical support, while deeper nodes were short and showed low posterior probabilities. Microsatellite data from inter simple sequence repeats (ISSR) proved uninformative. Based on the ITS sequence phylogeny, the members of the P. reediana species complex (as formerly defined) are not as closely related as previously suspected. Morphological characters, as well as biogeographical information, were compared to the resultant phylogeny and relevant species boundaries were defined according to the phylogenetic species concept. Several taxonomic changes were necessary. Physaria spatulata comb. nov. is no longer recognized as a subspecific taxon of P. reediana. However, Physaria reediana subsp. curvipes st. nov. is described as a subspecies of P. reediana due to the combination of evidence. Physaria pycnantha sp. nov. is clearly distinct from P. nelsonii, under which it was formerly circumscribed. Physaria pachyphylla sp. nov. and Physaria eriocarpa sp. nov., narrow endemics from Montana, were confirmed to be new species as a result of this study. Several factors (low statistical support for deeper branches, limited geographic distributions for some taxa, and morphological similarities) are indicative of a relatively recent radiation of, not only members under study here, but the genus as a whole. Achieving a coherent and useful taxonomy of this group of species came about only with the synthesis of the molecular, morphological, and biogeographical data.
Year of Submission
2005
Degree Name
Master of Science
Department
Department of Biology
First Advisor
Stephen O'Kane
Second Advisor
James W. Demastes
Third Advisor
James E. Jurgenson
Date Original
2005
Object Description
1 PDF file (127 leaves)
Copyright
©2005 Benjamin R. Grady
Language
en
File Format
application/pdf
Recommended Citation
Grady, Benjamin R., "Molecules, Morphology, and Biogeography: An Analysis of the Phylogeny and Taxonomy of the Physaria reediana Species Complex (Brassicaceae)" (2005). Dissertations and Theses @ UNI. 2781.
https://scholarworks.uni.edu/etd/2781
Comments
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