Date of Award

7-7-2020

Publication Type

Master Thesis

Degree Name

M.Sc.

Department

Biological Sciences

First Advisor

Oliver P. Love

Second Advisor

Daniel D. Heath

Keywords

Chinook salmon, Developmental Plasticity, Environmental-Match Hypothesis, Prenatal cortisol, Thermal Stress, Transcriptomics

Rights

info:eu-repo/semantics/openAccess

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Abstract

Into the next century, global climate change models predict chronic and acute thermal fluctuations to increase in intensity and frequency, especially in freshwater environments. Recent studies identified that maternal stress signals may alter offspring phenotype, which may confer some adaptive benefit when offspring experience similar stressful environments (Environmental-Match Hypothesis). Using this framework, I investigated if elevated rearing temperature conditions and maternal stress signals produced predictive adaptive responses through modifications to gene transcriptional profiles. I exposed Lake Ontario Chinook salmon (Oncorhynchus tshawytscha) eggs to a biologically relevant maternal stress signal (1000ng/mL cortisol bath or control) and divided eggs across two rearing temperatures that mimic current ambient and future (+3°C) thermal environments. We then evaluated gene transcriptional profiles and survival of offspring at three key developmental stages (i.e., eyed-egg, alevin, and fry) and gene transcription profiles in response to an acute, multiday thermal stressor (+9°C/day) later in life (i.e., parr). Overall, we found elevated rearing temperature environments altered transcriptional responses both during development and later in life. Elevated temperatures increased mortality and prenatal cortisol did not rescue survival of offspring reared under elevated temperature conditions. Prenatal cortisol had no significant effect on gene transcriptional profiles for any developmental stage, or in response to an acute thermal stressor later in life under either rearing condition. Therefore, prenatal cortisol may not be an effective inducer of intergenerational plasticity in response to chronic and acute thermal stress.

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