Softening and Cross-Susceptibility: Exposure to Heat and Desiccation Reduces Future Stress Tolerance in an Insect

Author

Lauren Harter, 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

Tara Thiemann

Second Committee Member

Jane Khudyakov

Abstract

The frequency and duration of environmental stressors, such as heat waves and drought, will continue to grow due to ongoing climate change, thereby increasing the likelihood that organisms will experience stressors consecutively. Exposure to one stressor can improve or impair future tolerance to the same stressor (i.e., hardening or softening, respectively), or enhance or reduce future tolerance to a different stressor (i.e., cross-protection or cross-susceptibility, respectively). Understanding whether stress improves or impairs animals’ abilities to withstand future stressors is critical for determining the physiological sensitivity of animals to ongoing climate change. Here, I evaluated the responses to consecutive heat and desiccation stressors in the variable field cricket (Gryllus lineaticeps). Given the potential energetic costs of hardening and cross-protection, I further examined whether resource acquisition (e.g., food consumption) promoted hardening and cross-susceptibility. Prior heat exposure reduced future heat tolerance (i.e., softening), and prior exposure to both heat and desiccation reduced future desiccation tolerance (i.e., softening and cross-susceptibility), potentially due to terminal reproductive investment. Further, resource acquisition (amount of body mass gained) did not influence stress tolerance because individuals that acquired more resources were not more likely to exhibit benefits (rather than costs) to their future stress tolerance. In sum, my results suggest the increasing frequency of climate-related stressors may pose a significant physiological risk to some animals.

Pages

30

Recommended Citation

Harter, Lauren. (2024). Softening and Cross-Susceptibility: Exposure to Heat and Desiccation Reduces Future Stress Tolerance in an Insect. University of the Pacific, Thesis. https://scholarlycommons.pacific.edu/uop_etds/4308