title: Do Hormones, Telomere Lengths, and Oxidative Stress form an Integrated Phenotype? A Case Study in Free-Living Tree Swallows.
abstract: 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.
authors.affiliation: *Department of Biology, University of Nevada Reno, 1664 N Virginia St, Reno, NV 89557, USA Department of Biological Sciences, Virginia Tech, 1405 Perry Street, Derring Hall, VA 24061, USA jouyang@unr.edu.
authors.forename: J Q
authors.initials: JQ
authors.lastname: Ouyang
authors.affiliation: Department of Biological Sciences, Virginia Tech, 1405 Perry Street, Derring Hall, VA 24061, USA Department of Evolutionary Zoology and Human Biology, University of Debrecen, Egyetem tér 1, Debrecen, 4032, Hungary.
authors.forename: Á Z
authors.initials: ÁZ
authors.lastname: Lendvai
authors.affiliation: Department of Biological Sciences, Virginia Tech, 1405 Perry Street, Derring Hall, VA 24061, USA.
authors.forename: I T
authors.initials: IT
authors.lastname: Moore
authors.affiliation: Department of Biological Sciences, Virginia Tech, 1405 Perry Street, Derring Hall, VA 24061, USA Department of Biology, Queen's University, Biosciences Complex, Kingston, Ontario K7L3N6, Canada.
authors.forename: F
authors.initials: F
authors.lastname: Bonier
authors.affiliation: Department of Biology, Bucknell University, 209 B, Lewisburg, PA 570-577-1310, USA.
authors.forename: M F
authors.initials: MF
authors.lastname: Haussmann
mesh_terms: D000818:Animals; D005260:Female; D005938:Glucocorticoids / Q000378:metabolism*; D000071421:Life History Traits; D008297:Male; D009864:Ontario; D018384:Oxidative Stress; D010641:Phenotype; D046388:Swallows / Q000235:genetics / Q000502:physiology*; D059505:Telomere Homeostasis; D059506:Telomere Shortening
chemical_list: D005938:Glucocorticoids