Dissertation
HOW DOES GENOMIC VARIATION UNDERLYING LOCALLY ADAPTED POPULATIONS SHIFT FOLLOWING A RAPID ENVIRONMENTAL CHANGE?
Washington State University
Doctor of Philosophy (PhD), Washington State University
01/2021
DOI:
https://doi.org/10.7273/000005454
Handle:
https://hdl.handle.net/2376/119642
Abstract
With an unprecedented rate of species loss caused by global climate change, emerging infectious disease and anthropogenic disturbance, identifying the adaptive potential of populations in response to various environmental stressors is crucial. Therefore, we need to have a clearer understanding of the interplay of various evolutionary forces on patterns of localized genetic variation following an extreme environmental change. In my dissertation research, I evaluated the impacts of novel selective pressures on the genomic variation underlying locally adapted populations, specifically in Tasmanian devils (Sarcophilus harrisii) and rainbow/steelhead trout (Oncorhynchus mykiss). In Tasmanian devils, I hypothesized that rapid evolutionary response to devil facial tumor disease (DFTD) may impact the distribution of adaptive genetic variation across the landscape. Using sequence capture data from over 3,000 devils collected island-wide, pre and post-DFTD arrival, I found strong selection imposed by DFTD may have swamped out signatures of local adaptation to the abiotic environment. Using transcriptomic data, I found enrichment of gene expression of putative locally adaptive genes. Taken together, these studies suggested that a novel selective pressure, DFTD, reduced functionally significant genetic variation involved in local adaptation to abiotic variables in devil populations. Similarly, I investigated the impacts of dam construction and removal on the evolution and maintenance of diverse life-history forms of rainbow/steelhead trout (O. mykiss). I hypothesized that selective pressures created by dams provided conditions favorable for resident phenotypes, thus selecting against genetic variation associated with the migratory phenotype. Using population genetic analyses, I found descendant steelhead from formerly above and below the dam populations rapidly recolonized the river, suggesting that dams did not significantly impact the evolution of Elwha River O. mykiss. Future work will include testing for shifts in genetic-environmental associations following dam removal to determine if O. mykiss populations became locally adapted to residential conditions following dam construction. The combination of these studies across two different systems in response to different environmental stressors revealed insight into the impacts of extreme changes on local patterns of standing genetic variation.
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Details
- Title
- HOW DOES GENOMIC VARIATION UNDERLYING LOCALLY ADAPTED POPULATIONS SHIFT FOLLOWING A RAPID ENVIRONMENTAL CHANGE?
- Creators
- Alexandra Kaye Fraik
- Contributors
- Joanna L Kelley (Advisor)Paul A Hohenlohe (Committee Member)David Crowder (Committee Member)Richard Gomulkiewicz (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- School of Biological Sciences
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 162
- Identifiers
- 99900591956701842
- Language
- English
- Resource Type
- Dissertation