The Past, Present, and Future of Climate Adaptation in a Widespread Lizard Species

Author

• Matthew R. McTernan, Clemson UniversityFollow

Date of Award

8-2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biological Sciences

Committee Chair/Advisor

Dr. Christopher Parkinson

Committee Member

Dr. Michael Sears

Committee Member

Dr. Matthew Koski

Committee Member

Dr. Christopher Saski

Committee Member

Dr. Shane Campbell-Staton

Abstract

Climate, as a selective force, shapes patterns of biodiversity globally. However, how species adapt to climate remains a central question of biology. The need to understand climate adaptation is paramount, as global climate change threatens a large portion of global diversity. Climate can impose selection on life by either controlling rates of energy intake and expenditure through effects on body temperature and activity, or by exposing organisms to conditions beyond their physiological limits. Studies of climate adaptation have identified a wide-range of putatively adaptive phenotypic patterns, but genomic evidence is increasingly being used to investigate these patterns and better understand how organisms adaptively respond to selection imposed by climate. In this dissertation, I utilize a combination of phylogenetic, demographic, biophysical, and ecological genomic methods to investigate climate adaptation in a widespread lizard species, the Eastern fence lizard (Sceloporus undulatus). I first investigated general patterns of genomic variation across the species range. I then used biophysical models to estimate aspects of potential activity and nest conditions for populations across the species range, as these are likely primary drivers of selection by climate on S. undulatus. I used outputs from the biophysical models to identify patterns of putatively adaptive genomic variation, and found signatures of selection on genes that enrich for two pathways: the calcium-signaling pathway and gonadotropin-releasing hormone pathway. Lastly, I assess the potential for S.undulatus to respond to future climate change. Altogether, my dissertation provides important genomic evidence that furthers our understanding of how the Sceloporus undulatus, a widespread lizard species and longstanding model system for the study of climate adaption, adapts to climate.

Recommended Citation

McTernan, Matthew R., "The Past, Present, and Future of Climate Adaptation in a Widespread Lizard Species" (2026). All Dissertations. 4360.
https://open.clemson.edu/all_dissertations/4360

Author ORCID Identifier

0000-0002-8962-5802