Date of Award

2017

Degree Type

Thesis

Degree Name

M.Sc.

Department

Biological Sciences

First Advisor

Love, Oliver

Second Advisor

Semeniuk, Christina

Keywords

Behaviour, Cortisol, Fish, Maternal effects, Pacific salmon, Stress

Rights

CC BY-NC-ND 4.0

Abstract

Assessing the intergenerational effects of stress is an important factor in determining how populations will respond to changing environments. Stressful maternal environments often lead to perceived negative effects on offspring phenotype (e.g., small size, slow growth, high fearfulness/anxiety), yet these changes may better equip offspring for stressful conditions (i.e., environmental matching), showing that intergenerational effects have the potential to dampen negative effects of environmental stressors. This thesis aims to test this theory by manipulating a maternal signal of stress and measuring offspring phenotype and performance in multiple environments. I treated Chinook salmon (Oncorhynchus tshawytscha) eggs with cortisol (low dose (LD), high dose (HD), control dose (CD)) and found that LD and HD groups had higher embryonic survival than the CD group and HD fish were smaller than CD fish at yolk-sac absorption. Following a 30-day post-natal stressor (low water depths in stream channels), juvenile fish from the LD group in low water conditions displayed optimal phenotypic/performance traits, based on measures of size, physiology, and behaviour. However, traits measured in the HD group were sub-optimal, indicating that fish were likely prepared for a more severely stressful environment. The CD group only displayed some indicators of being mismatched to the low water conditions, which may have been more apparent should conditions have been chronically stressful. Collectively, my results emphasize the potential for positive earlylife effects of maternally-derived stress and support environmental matching theory while showing detrimental effects of unreliable cues. As environments change rapidly and also become more unpredictable, it is timely to further determine the outcomes of intergenerational stress in both matched and mismatched future environments.

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