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Earhart, Madison

University of British Columbia

How organisms respond to environmental change is a fundamental question in biology, critical to our understanding of how animals will cope with climate change. Determining the climate change resilience of a species or population is a challenging task, as resilience can be influenced by phenotypic plasticity and genetic variation. Specifically in aquatic habitats, organisms encounter rapid environmental changes including variations in temperature, oxygen availability, and salinity which occur across different spatial and temporal scales. My thesis aimed to explore how plasticity and adaptation influence resilience to environmental change across these scales in three different fish species. The three species I studied were Atlantic killifish (Fundulus heteroclitus), white sturgeon (Acipenser transmontanus), and rainbow trout (Oncorhynchus mykiss). I measured whole-animal physiology and underlying molecular mechanisms to assess responses to climate change stressors across developmental stages and populations. In killifish and white sturgeon, I found that exposure to climate change stressors during development had lasting phenotypic effects and affected the plasticity of many traits. These studies underlined the importance of considering developmental stage when evaluating stressor effects, as individuals must persist despite environmental changes during sensitive life stages to survive. Also, in white sturgeon and killifish I demonstrated the impacts of simultaneous stressors on whole-animal performance and the underlying genetic mechanisms highlighting the detrimental impact of compounding stressors. To investigate the role genetic variation plays on the ability of fishes to cope with environmental change I assessed how adaptation to different environments can affect the stress response or survival in novel environments. I found that local adaptation can influence the magnitude and plasticity of the stress-axis in killifish, highlighting the potential for adaptive tradeoffs between the stress response, body condition, and survival in the wild. In rainbow trout, I found that adaptation to hatchery environments impacts offspring phenotypes and decreases survival in the wild, highlighting the interplay between adaptation and coping with novel stressors. My thesis contributes to our understanding of the basic biological question, “how do fishes cope with environmental change?”, and also provides evidence for concrete actions and conservation-management recommendations during climate change.

Text

2024-01-08

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/87159

Zoology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/