title: Marker-dependent associations among oxidative stress, growth and survival during early life in a wild mammal.
abstract: Oxidative stress (OS) is hypothesized to be a key physiological mechanism mediating life-history trade-offs, but evidence from wild populations experiencing natural environmental variation is limited. We tested the hypotheses that increased early life growth rate increases OS, and that increased OS reduces first-winter survival, in wild Soay sheep (Ovis aries) lambs. We measured growth rate and first-winter survival for four consecutive cohorts, and measured two markers of oxidative damage (malondialdehyde (MDA), protein carbonyls (PC)) and two markers of antioxidant (AOX) protection (total AOX capacity (TAC), superoxide dismutase (SOD)) from blood samples. Faster lamb growth was weakly associated with increased MDA, but not associated with variation in the other three markers. Lambs with higher SOD activity were more likely to survive their first winter, as were male but not female lambs with lower PC concentrations. Survival did not vary with MDA or total TAC. Key predictions relating OS to growth and survival were therefore supported in some OS markers, but not others. This suggests that different markers capture different aspects of the complex relationships between individual oxidative state, physiology and fitness, and that overarching hypotheses relating OS to life-history variation cannot be supported or refuted by studying individual markers.
authors.affiliation: Institute of Biological and Environmental Sciences, School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK louise.christensen.08@aberdeen.ac.uk.
authors.forename: Louise L
authors.identifier: 0000-0002-5177-7229
authors.initials: LL
authors.lastname: Christensen
authors.affiliation: Glasgow Ageing Research Network (GARNER), Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow AB24 2TZ, UK.
authors.forename: Colin
authors.initials: C
authors.lastname: Selman
authors.affiliation: College of Life and Environmental Sciences, University of Exeter, Penryn Campus, TR10 9EZ, UK.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Blount
authors.affiliation: Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3JG, UK.
authors.forename: Jill G
authors.initials: JG
authors.lastname: Pilkington
authors.affiliation: Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3JG, UK.
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Watt
authors.affiliation: Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3JG, UK.
authors.forename: Josephine M
authors.initials: JM
authors.lastname: Pemberton
authors.affiliation: Institute of Biological and Environmental Sciences, School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK.
authors.forename: Jane M
authors.initials: JM
authors.lastname: Reid
authors.affiliation: Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3JG, UK.
authors.forename: Daniel H
authors.identifier: 0000-0002-9985-0317
authors.initials: DH
authors.lastname: Nussey
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D005260:Female; D008136:Longevity; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D018384:Oxidative Stress; D012756:Sheep / Q000254:growth & development*; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D000975:Antioxidants; D008315:Malondialdehyde; D013482:Superoxide Dismutase
keywords: Soay sheep; antioxidants; early life fitness; life-history trade-offs; oxidative damage; plasma