Measuring and understanding senescence in a wild population

Brown, Thomas (2022) Measuring and understanding senescence in a wild population. Doctoral thesis, University of East Anglia.

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Senescence – the decline in organismal function and performance – frequently occurs in many taxa. However, within- and between- populations of the same species there can be considerable variation in the onset and rate of senescence. Understanding the causes and fitness consequences of differential senescence is a key objective in the study of life-history evolution and gerontology. Wild populations are uniquely suited for exploring the role of complex genetic, environmental and social contributions to senescence patterns. However, accurately measuring the severity of senescence at the individual-level has presented a long-standing challenge. In this thesis, I explore the utility of several candidate intrinsic markers of senescence in a closely monitored wild population of Seychelles warblers (Acrocephalus sechellensis). Firstly, I reveal complex relationships between haematocrit, age a survival, which suggest haematocrit could be used as a marker of early-life stress. Secondly, I show that telomere dynamics (i.e. the increase and decrease in telomere length within-individuals) reflect life-history costs in females, such as reproductive effort and malarial infections, and subsequently impacts future mortality risk. Thirdly, I find evidence of a silver-spoon effect, whereby individuals in better condition (mass adjusted size) as juveniles have higher survival probabilities throughout adult-life but does not affect patterns of survival- or reproductive senescence. Lastly, I develop a ribosomal DNA-methylation clock for predicting age and survival, with substantially improved accuracy over previously used markers; telomere length and condition. With the combined use of multiple intrinsic markers, this study reveals the dynamic and varied ways in which fitness-related traits change with age in a single species. Based on these findings, I discuss the relative strengths and weaknesses of different intrinsic markers for improving our understanding of ageing, senescence and life-history in wild populations

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Chris White
Date Deposited: 08 Aug 2022 13:42
Last Modified: 08 Aug 2022 13:42

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