Dissertation
EVOLUTIONARY GENETICS OF RANGE LIMITS IN AN ENDEMIC SALAMANDER (AMBYSTOMA BARBOURI)
Doctor of Philosophy (PhD), Washington State University
01/2016
Handle:
https://hdl.handle.net/2376/118141
Abstract
Despite decades of interest in range limits, the evolutionary and ecological processes that lead to geographic distributions of organisms lack empirical evidence. In this dissertation, I test major abiotic range limit hypotheses in the streamside salamander (Ambystoma barbouri) to provide empirical evidence for abiotic processes that lead to geographic distributions. A. barbouri is an ideal organism for testing range limit hypotheses due to its specialized distribution in the eastern United States that is not defined by any conspicuous barriers. Thus, this dissertation has three objectives which all seek to understand range limits; 1) determine genetic patterns across the distribution of A. barbouri and how they might influence the range, 2) identify resistant habitat across the distribution of A. barbouri which may prevent dispersal beyond the range, and 3) investigate patterns of local adaptation between edge and center populations to determine if edges are adapted to their local environments. In Chapter 1, I provided a test for the central-marginal hypothesis using genetic samples from three broad transects of A. barbouri which show that most edge populations are acting like sinks and may not have the genetic diversity and effective population sizes to adapt beyond the range edge. In Chapter 2, I utilized landscape genetic analyses to determine both regional and range-wide resistant habitat that becomes more common towards the edges of the distribution which can prevent further dispersal of A. barbouri. In Chapter 3, I used population genetic analyses to determine asymmetric gene flow from core populations to edge populations. I additionally performed a reciprocal transplant experiment to show that gene flow can inhibit local adaptation in edge populations. Finally, in Chapter 4, I performed genomic sequencing of populations across the distribution of A. barbouri to determine adaptive loci associated with different regions and identify adaptive genetic patterns from core to edge. Overall, this dissertation provides some of the first tests for abiotic range limit hypotheses in vertebrate systems and serves as a framework for understanding range limits in other organisms.
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Details
- Title
- EVOLUTIONARY GENETICS OF RANGE LIMITS IN AN ENDEMIC SALAMANDER (AMBYSTOMA BARBOURI)
- Creators
- Steven James Micheletti
- Contributors
- Andrew Storfer (Advisor)Jeremiah W Busch (Committee Member)Paul A Hohenlohe (Committee Member)Lisette P Waits (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
- 198
- Identifiers
- 99900581520201842
- Language
- English
- Resource Type
- Dissertation