Plasticity in Response to Temperature Magnitude and Variation---from Life History to Thermal Tolerance and Coloration

Author

Austin Rex Hoffman, University of the PacificFollow

Date of Award

2024

Document Type

Thesis

Degree Name

Master of Science (M.S.)

Department

Biological Sciences

First Advisor

Zachary Stahlschmidt

First Committee Member

Marcos Gridi-Papp

Second Committee Member

Ryan Hill

Abstract

Warming associated with climate change has many direct and downstream effects on animals. For example, warmer developmental temperatures can improve heat tolerance and reduce insect melanization, which is related to coloration, thermoregulation, immunity, desiccation resistance, and potentially life-history traits, such as investment into reproduction and dispersal. Increased temperature variation is also a feature of climate change, and it may have a larger impact on animals than warming. However, I lack insight into the combined effects of temperature magnitude and variability on important traits of life history, thermal tolerance, and coloration. Thus, I integrated temperature variation into thermal performance using a factorial manipulation of temperature magnitude (mean: 20, 25, and 30℃) and daily temperature fluctuation (±0, 5, and 10℃) during development in the variable field cricket (Gryllus lineaticeps). I tested hypotheses in which temperature variation would (1) be generally costly and, thus, reduce trait performance across all temperature magnitudes, or (2) interact with temperature magnitude resulting in benefits to trait performance at low temperature magnitude (20℃) and costs at high temperature magnitude (30℃). I found no support for my first hypothesis, but my results for most life-history traits and some cold tolerance traits supported my second hypothesis. I generally show that warmer, more thermally variable environments of the future may be particularly costly to some animals. Yet, my results indicate that melanization can respond to both warming and temperature variation, suggesting that thermal plasticity in coloration may be an important mechanism in mitigating the effects of climate change.

Pages

48

Recommended Citation

Hoffman, Austin Rex. (2024). Plasticity in Response to Temperature Magnitude and Variation---from Life History to Thermal Tolerance and Coloration. University of the Pacific, Thesis. https://scholarlycommons.pacific.edu/uop_etds/4309