Dissertation
DIVERSIFICATION AND SPECIES BOUNDARIES IN THE WESTERN NORTH AMERICAN FLORA: CASE STUDIES FORM THE CLEOMACEAE AND THE GENUS ASCLEPIAS
Doctor of Philosophy (PhD), Washington State University
01/2015
Handle:
https://hdl.handle.net/2376/111612
Abstract
Western North American physiography is characterized by considerable habitat heterogeneity accompanied by temporal environmental changes associated with climate fluctuations during the recent Pleistocene. This heterogeneity is a major driver the process of diversification, especially when distributions become allopatric or parapatric. Processes related to recently diverged taxa such as incomplete lineage sorting and hybridization are a challenge to species-level and above-species level studies of the evolution of the western North American flora.
The North American cleomoids (Cleomaceae), a monophyletic group composed of five genera, poorly defined generic boundaries although species are reasonably well delimited. This detailed phylogenetic investigation generated a phylogenetic framework to assess generic monophyly and test historical evolutionary hypotheses regarding phylogeny and evolution of fruit type in this group.
Four diminutive species of Asclepias found in western North America, termed the dwarf milkweed group, exhibit observable, but subtle, morphological differences corresponding to their allopatric distributions. I analyzed microsatellite markers to explore species boundaries in this group. Bayesian genetic structuring, approximate Bayesian computation, assessments of genetic distance discontinuities, and ecological niche modeling were used to explore species boundaries and inform taxonomic choices regarding the species status of these four dwarf milkweeds.
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Details
- Title
- DIVERSIFICATION AND SPECIES BOUNDARIES IN THE WESTERN NORTH AMERICAN FLORA: CASE STUDIES FORM THE CLEOMACEAE AND THE GENUS ASCLEPIAS
- Creators
- James P. Riser II
- Contributors
- Eric H. Roalson (Advisor)Jeremiah W. Busch (Committee Member)Mark Fishbein (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Biological Sciences, School of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 128
- Identifiers
- 99900581730301842
- Language
- English
- Resource Type
- Dissertation