Term of Award

Spring 2020

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Biology

Committee Chair

Christian L. Cox

Committee Member 1

Joshua D. Gibson

Committee Member 2

Lance D. McBrayer

Abstract

Organisms may respond to climate change through behavior, genetic adaptation, and/or phenotypic plasticity. Tropical ectotherms are thought to be especially vulnerable to climate change because most have a narrow range of thermal tolerance while living close to their upper thermal tolerance limits. Additionally, many tropical species live in closed-canopy forests, which provide homogenous thermal landscapes that prevent behavioral compensation for stressfully warm temperatures. Finally, tropical ectotherms are thought to have decreased capacity for phenotypic plasticity because they have evolved in thermally stable environments. We tested gene expression patterns and phenotypic plasticity in the Panamanian slender anole by a) measuring changes in gene expression in response to, short-term temperature change (two hours) and b) using a mesocosm experiment to measure phenotypic plasticity in response to longer-term thermal stress (one month). In response to short-term exposure, we found the brain, liver, and muscle differentially expressed genes (DEGs) that coded for heat shock proteins. Interestingly, all three tissues displayed a greater gene expression response to warm conditions relative to cool conditions. During longer-term exposure (mesocosm experiment), we found that lizards exposed to heat treatment had increased VTmax and had limited plasticity of thermoregulatory behavior. Our results provide evidence that tropical forest lizards can use gene expression and phenotypic plasticity to respond to shifting environmental temperatures, despite having evolved under thermally stable conditions. This work suggests that genomic regions that regulate pathways of heat shock response will likely be under selection in response to global climate change. Gene expression and phenotypic plasticity are processes that should be considered when predicting the future of tropical ectotherms under a changing climate.

Research Data and Supplementary Material

No

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