Do Hormones, Telomere Lengths, and Oxidative Stress form an Integrated Phenotype? A Case Study in Free-Living Tree Swallows

Synopsis All organisms must anticipate and balance energetic demands and available resources in order to maximize fitness. As hormones coordinate many interactions between an organism’s internal condition and the external environment, they may be key in mediating the allocation of resources to meet...

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Published in:Integrative and comparative biology 2016-08, Vol.56 (2), p.138-145
Main Authors: Ouyang, J. Q., Lendvai, Á. Z., Moore, I. T., Bonier, F., Haussmann, M. F.
Format: Article
Language:English
Subjects:
Animals
Evolutionary Endocrinology: Hormones as Mediators of Evolutionary Phenomena
Female
Glucocorticoids - metabolism
Life History Traits
Male
Ontario
Oxidative Stress
Phenotype
Swallows - genetics
Swallows - physiology
Telomere Homeostasis
Telomere Shortening
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Summary:Synopsis All organisms must anticipate and balance energetic demands and available resources in order to maximize fitness. As hormones coordinate many interactions between an organism’s internal condition and the external environment, they may be key in mediating the allocation of resources to meet these demands. However, given that individuals differ considerably in how they react to changes in energetic demand, we asked whether variations in endocrine traits also correspond with life history variation. We tested whether natural variation in glucocorticoid hormone levels, oxidative stress measurements, and condition related to reproductive effort in a free-living songbird, the tree swallow, Tachycineta bicolor. We then tested whether any of these traits predicted the probability of a particular individual’s return to the local population in the following two years, an indicator of survival in this philopatric species. We found that males and females with longer telomeres had lighter nestlings. Moreover, individuals with lower plasma antioxidant capacity and higher reactive oxygen metabolites (i.e., greater oxidative stress) were less likely to return to the population. However, none of these traits were related to glucocorticoid levels. Our findings suggest a trade-off between reproduction and survival, with individuals with shorter telomeres having heavier nestlings but potentially paying a cost in terms of higher oxidative stress and lower survival. Interestingly, the evidence of this trade-off was unrelated to natural variation in glucocorticoids.
ISSN:1540-7063
1557-7023
DOI:10.1093/icb/icw044