The role of intrinsic and extrinsic factors in shaping alternative migratory tactics and metabolic phenotypes in brown trout

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dc.contributor.advisor Reed, Thomas en
dc.contributor.advisor Mcginnity, Philip en Archer, Louise C. 2020-05-20T09:57:59Z 2020-05-20T09:57:59Z 2019-11 2019-11
dc.identifier.citation Archer, L. C. 2019. The role of intrinsic and extrinsic factors in shaping alternative migratory tactics and metabolic phenotypes in brown trout. PhD Thesis, University College Cork. en
dc.identifier.endpage 264 en
dc.description.abstract Variation among and within populations accounts for a considerable portion of phenotypic diversity produced in nature, and is instrumental to the structure and function of ecosystems. Understanding how, and why, intraspecific diversity persists is essential for predicting and managing the effects of global change, particularly because intraspecific variation may mediate diverse responses to changes in the environment. Alternative phenotypes – i.e. discrete phenotypic variation – can arise from a combination of proximate and ultimate mechanisms. Proximate mechanisms reflect how environmental factors shape phenotypic variation via intermediate physiological processes, which can themselves vary and be decomposed into genetic versus environmental components. Ultimate mechanisms concern the evolutionary function of a given phenotype. In this thesis, I explore how proximate and ultimate factors contribute to a particularly striking example of intraspecific diversity: alternative migratory tactics in brown trout Salmo trutta. Brown trout are iconic for the variety of migratory life histories they exhibit; yet fundamental knowledge gaps remain regarding how environmental, physiological, and genetic factors integrate to underpin life history decisions among and within populations. In Chapter 2, I assessed how food restriction and population background influences the expression of migratory tactics in offspring from two populations that naturally differ in anadromy (i.e. sea-migration). Food restriction affected traits related to size and condition, and resulted in a higher frequency of anadromy in both populations, though populations varied in their responses according to the timing of food restriction treatments. While anadromy was overall more frequent in offspring from the naturally anadromous population, the expression of anadromous phenotypes in offspring from a non-anadromous population indicated that migratory tactics might emerge in response to unfavourable environmental conditions causing energetic limitation. In Chapter 3, I further considered proximate mechanisms by exploring how multiple environmental factors (food and temperature) influence migration. Antagonistic effects of food restriction and increased temperature on condition and size-related traits were not translated at the level of migration tactics, where effects of food restriction and temperature were additive, but opposing (food restriction increased anadromy, whereas temperature decreased anadromy). I explored how components of metabolic rate – a fundamental determinant of physiological status – varied according to food restriction and population background in Chapter 4. Standard metabolic rate (SMR) was lower in food-deprived fish, while SMR, maximum metabolic rate, and aerobic scope (AS) were higher in offspring from a naturally anadromous population compared to a non-anadromous population. Population-specific effects of food restriction on AS also emerged. I further addressed the causes and consequences of metabolic rate variation in Chapter 5, where I found metabolic traits varied according to both population background and temperature, with important consequences for growth rates (a key fitness-related trait that can shape life histories). Collectively, these results contribute to our knowledge of how environmental and genetic factors underpin life-history diversity in terms of migratory tactics and physiology. Changes in environmental conditions will likely alter patterns of life-history diversity (mediated by changes in individual physiology) in ways that will also depend on population-specific factors. While predicting the impacts of multi-faceted environmental change will be complex, knowledge of the links between physiology, environment, and ultimately, life history, is crucial for conserving important biodiversity within brown trout, a species that is already in widespread decline due to pervasive global change. en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher University College Cork en
dc.rights © 2019, Louise C. Archer. en
dc.rights.uri en
dc.subject Salmo trutta en
dc.subject Climate change en
dc.subject Proximate drivers en
dc.subject Genotype by environment en
dc.subject Partial migration en
dc.subject Aquatic en
dc.subject Brown trout en
dc.subject Multiple stressors en
dc.subject Antagonistic en
dc.subject Metabolic en
dc.subject Plasticity en
dc.title The role of intrinsic and extrinsic factors in shaping alternative migratory tactics and metabolic phenotypes in brown trout en
dc.type Doctoral thesis en
dc.type.qualificationlevel Doctoral en
dc.type.qualificationname PhD - Doctor of Philosophy en
dc.internal.availability Full text available en
dc.description.version Accepted Version en
dc.contributor.funder European Research Council en
dc.description.status Not peer reviewed en Biological, Earth and Environmental Sciences en
dc.internal.conferring Summer 2020 en
dc.internal.ricu Aquaculture & Fisheries Development Centre en
dc.internal.ricu Environmental Research Institute (ERI) en
dc.relation.project info:eu-repo/grantAgreement/EC/H2020::ERC::ERC-STG/639192/EU/Alternative life histories: linking genes to phenotypes to demography/ALH en
dc.availability.bitstream openaccess

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© 2019, Louise C. Archer. Except where otherwise noted, this item's license is described as © 2019, Louise C. Archer.
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