Portland State University. Department of Biology
Term of Graduation
Date of Publication
Master of Science (M.S.) in Biology
Eriophyllum, Polyploidy, Niche (Ecology)
1 online resource (v, 51 pages)
The high rates of polyploidization events in angiosperms is a well-documented driver of diversification and speciation. The consequences of polyploidy--from gene expression up to ecology--and the processes facilitating the persistence of polyploidy in its early establishment in populations are poorly understood. In this thesis, I examined the role of recurrent formation, ecological differentiation, and secondary dispersal via biotic vectors in the maintenance and persistence of an intervarietal polyploid contact zone of Eriophyllum lanatum in Southern Oregon. Sampling 35 total populations, I used a whole chloroplast capture and flow cytometry to determine the diversity and distribution of chloroplast haplotypes and estimate the number of origins of polyploidy. Comparative ecological niche modeling was used to evaluate the relationship of the tetraploid ecological niche to the diploid niche and to measure niche overlap and niche breadth. Finally, I used a landscape genetics approach to examine patterns of seed dispersal in the contact zone. I identified 7 independent polyploidization events, indicating that recurrent formation has played an important role in maintaining polyploid populations. There was a high degree of niche overlap in diploids and tetraploids, although tetraploids occupied a slight broader niche than diploids. I found better support for an isolation by resistance model over isolation by distance model for patterns of seed dispersal. The contributions of canopy and elevation to the best supported model are consistent with secondary seed dispersal by biotic vectors, most likely hoof-epizoochory by ungulates.
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Diaz, Nicolas Alexander, "Recurrent Formation, Low Levels of Ecological Differentiation, and Secondary Dispersal Facilitate the Establishment and Persistence of Autopolyploids in Eriophyllum lanatum" (2020). Dissertations and Theses. Paper 5556.