Dissertation
INTEGRATION OF COMPARATIVE PHYLOGENETICS AND GENOMICS TO STUDY DIVERSIFICATION AND HISTORICAL DEMOGRAPHY
Doctor of Philosophy (PhD), Washington State University
01/2020
Handle:
https://hdl.handle.net/2376/117600
Abstract
Evolutionary biology is a comparatively young field of study. Spurred on by the modern synthesis, evolutionary biology rapidly developed and today encompasses a diversity of distinct, but often overlapping research programs. For instance, one critical development was in efforts to understand the nature of species formation, as well as the maintenance of species boundaries. Although in conflict with the historically significant biological species concept, there has been increasing recognition that hybridization (interspecific mating) not only does occur among species but may even facilitate the generation of new species. However, the extent to which hybridization impacts rates of speciation and extinction has not yet been tested. Recently, conservation genetics, an extension of population genetics, has emerged as a useful approach to inform the management of imperiled species. One such species, the Tasmanian devil, is potentially threatened with extinction by a transmissible cancer, Devil Facial Tumor Disease (DFTD). Restricted to the island of Tasmania, devils have low present-day genetic diversity, a fact that potentially limits their capacity to respond to this novel threat. A better understanding of the historical context for this low genetic diversity may prove useful to interpreting the threat DFTD poses to devils. Likewise, without an understanding of the epidemiology of DFTD, that is how the disease spread across the island and the rates of transmission through time, active conservation management may be misled. Although efforts were made early in the disease outbreak to characterize the epidemiology of DFTD, such studies are lacking for late in the epizootic. Herein, I conduct three studies addressing the knowledge gaps outlined above. First, I conduct a comparative phylogenetic assessment of the role hybridization plays in the diversification process across all salamanders (Order Caudata) and show that hybridization may accelerate speciation. Second, I use whole genomes of twelve Tasmanian devils to reconstruct their demographic history, providing evidence that their low present-day genetic diversity is the consequence of historical geological and climatic processes. Lastly, I conduct a phylodynamic study of DFTD using 51 whole genomes and demonstrate that contrary to expectation the disease progression is slowing, providing cautious optimism for this imperiled species.
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Details
- Title
- INTEGRATION OF COMPARATIVE PHYLOGENETICS AND GENOMICS TO STUDY DIVERSIFICATION AND HISTORICAL DEMOGRAPHY
- Creators
- Austin H Patton
- Contributors
- Andrew Storfer (Advisor)Richard Gomulkiewicz (Committee Member)Luke J Harmon (Committee Member)Joanna L Kelley (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
- 210
- Identifiers
- 99900581613201842
- Language
- English
- Resource Type
- Dissertation