Egg glucocorticoids and maternal stressor exposure as modulators of offspring quality in Pacific salmon
department or school: Forestry, Faculty of
data provider: DSpace
degree campus: UBCV
creator: Sopinka, Natalie Marie
issued: 2015-03-02T20:16:42Z
issued: 2015
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: Maternal experiences can have profound effects on offspring phenotype. In oviparous animals, prolonged maternal exposure to stressors can elevate circulating cortisol and is thought to also elevate egg cortisol. Experimental increases in egg cortisol are known to affect offspring performance. In fishes, past research has focused on how chronic maternal exposure to stressors affects egg size and embryonic survival, but changes to egg hormones and progeny phenotype beyond early development are not well understood. The aim of this thesis was to test the hypothesis that maternal exposure to a stressor alters behavioural and physiological attributes of offspring, and that those alterations are mediated by increases in egg cortisol. The research focused on Pacific salmon; animals that, as adults, encounter diverse stressors during their once-in-a-lifetime migration to spawning areas. I found that experimentally elevating egg cortisol, mimicking the presumed outcome of maternal stress, modified offspring morphology, swimming performance, and behavioural responses to conspecific intruders and simulated predator attacks. However, when I chronically exposed females to a daily chase stressor during sexual maturation, egg cortisol at spawning was not affected. Despite the absence of differences in egg hormone content, maternal stressor exposure did have latent effects on offspring swimming performance and physiological stress responses. Collectively, the evidence presented in this thesis suggests that, in Pacific salmon, experimentally manipulating egg cortisol elicits changes in offspring, but maturing females may have the capacity to buffer eggs from increases in cortisol. Gametic properties other than the concentration of cortisol are likely affected by maternal stress and responsible for the observed changes to offspring performance. The multidirectional effects of maternal stress and egg cortisol treatment on offspring traits I report in this thesis support an emerging not…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/52312
note: EGG GLUCOCORTICOIDS AND MATERNAL STRESSOR EXPOSURE AS MODULATORS OF OFFSPRING QUALITY IN PACIFIC SALMON by NATALIE MARIE SOPINKA B.Sc., McMaster University, 2009 M.Sc., McMaster University, 2010 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (Forestry) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) February 2015 © Natalie Marie Sopinka, 2015 ii Abstract Maternal experiences can have profound effects on offspring phenotype. In oviparous animals, prolonged maternal exposure to stressors can elevate circulating cortisol and is thought to also elevate egg cortisol. Experimental increases in egg cortisol are known to affect offspring performance. In fishes, past research has focused on how chronic maternal exposure to stressors affects egg size and embryonic survival, but changes to egg hormones and progeny phenotype beyond early development are not well understood. The aim of this thesis was to test the hypothesis that maternal exposure to a stressor alters behavioural and physiological attributes of offspring, and that those alterations are mediated by increases in egg cortisol. The research focused on Pacific salmon; animals that, as adults, encounter diverse stressors during their once-in-a-lifetime migration to spawning areas. I found that experimentally elevating egg cortisol, mimicking the presumed outcome of maternal stress, modified offspring morphology, swimming performance, and behavioural responses to conspecific intruders and simulated predator attacks. However, when I chronically exposed females to a daily chase stressor during sexual maturation, egg cortisol at spawning was not affected. Despite the absence of differences in egg hormone content, maternal stressor exposure did have latent effects on offspring swimming performance and physiological stress responses. Collectively, the evidence presented in this thesis suggests that, in Pacific salmon, exp…
has type: Thesis/Dissertation
date issued: 2015-05
is shown at: 10.14288/1.0167691
language: eng
degree discipline: Forestry
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivs 2.5 Canada
rights URI: http://creativecommons.org/licenses/by-nc-nd/2.5/ca/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/52312