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Full text release has been delayed at the author's request until September 01, 2025

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Phylogeography and Range Limit Evolution in the Cumberland Plateau Salamander, Plethodon kentucki

Watts, Emily F.
http://orcid.org/0000-0001-6018-4428
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1691505419738269

Abstract Details

2023, Doctor of Philosophy (PhD), Ohio University, Biological Sciences (Arts and Sciences).
Gene flow and geography are critically influential factors in shaping the genetic history of a species. Gene flow can have beneficial effects on a population that may allow for new adaptations to occur, such as increasing genetic variation. However, gene flow may also result in negative consequences for populations if their fitness is decreased through the introduction of non-optimized traits or through selection resulting in a reduction of locally adapted individuals. Asymmetrical gene flow can even prevent local adaptation in edge populations when gene flow from central populations adapted to central conditions swamps locally adapted populations. This phenomenon can prevent a species from expanding its range, as it is unable to adapt to local conditions at the range edges. Thus, patterns of gene flow can determine the extent to which gene flow slows or promotes adaptation. Gene flow can also create problems for the inference of species relationships, because it is a source of gene tree-species tree discordance. While speciation is commonly modeled as a finite event, divergence is a process. Even after divergence, hybridization is common, and neglecting to account for it can lead to incorrect species tree inference. Nonetheless, the development of species tree inference methods that account for gene flow remains in its infancy. Even with the addition of more loci from genomic-scale data, gene flow misleads phylogenetic reconstruction. Thus, it is vital to account for gene flow with phylogenetic networks when inferring species relationships. This dissertation examines the role of gene flow in constraining adaptation in the Cumberland Plateau Salamander, Plethodon kentucki, a cryptic species with respect to the sympatric Northern Slimy Salamander, Plethodon glutinosus. After its description in 1983 by Highton and MacGregor using allozyme data, its taxonomic status was unclear, as the authors reported extreme levels of genetic differentiation for a single species with a narrow distribution, and follow-up studies found patterns of genetic variation that were discordant with the allozyme data. In chapter 1, I describe genetic variation within P. kentucki and conclude it is best recognized as a single species with substantial genetic structure within its limited distribution. In chapter 2, I describe the heterogeneity of the landscape within the range of P. kentucki. I also quantify the genetic connectivity across the range of P. kentucki and describe how the two interact to maintain the range of P. kentucki. I also test a novel theory about how different types of range edges impact adaptation at the periphery of a species’ range. This dissertation also examines the role of gene flow in confounding phylogenetic inference using two prominent phylogenetic network methods. In chapter 3, I use computer modeling to examine how these two methods perform under varying degrees of gene flow and population history, as well as how they perform under two different datasets. This dissertation explores the role of gene flow, or lack thereof, in maintaining species boundaries, inhibiting range expansion, and confounding the inference of species relationships.
Shawn Kuchta (Advisor)
John Schenk (Committee Member)
Diego Alvarado-Serrano (Committee Member)
Susan Williams (Committee Member)
129 p.
Biology; Evolution and Development
Plethodon kentucki; Speciation; Phylogeography; Range limit evolution; Phylogenetic networks

Recommended Citations

Citations

  • Watts, E. F. (2023). Phylogeography and Range Limit Evolution in the Cumberland Plateau Salamander, Plethodon kentucki [Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1691505419738269

    APA Style (7th edition)

  • Watts, Emily. Phylogeography and Range Limit Evolution in the Cumberland Plateau Salamander, Plethodon kentucki. 2023. Ohio University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1691505419738269.

    MLA Style (8th edition)

  • Watts, Emily. "Phylogeography and Range Limit Evolution in the Cumberland Plateau Salamander, Plethodon kentucki." Doctoral dissertation, Ohio University, 2023. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1691505419738269

    Chicago Manual of Style (17th edition)

ohiou1691505419738269
© 2023, all rights reserved.
This open access ETD is published by Ohio University and OhioLINK.