title: Starting with a handicap: effects of asynchronous hatching on growth rate, oxidative stress and telomere dynamics in free-living great tits.
abstract: A trade-off between resource investment into growth rate and body self-maintenance is likely to occur, but the underlying molecular mediators of such a trade-off remain to be determined. In many altricial birds, hatching asynchrony creates a sibling competitive hierarchy within the brood, with first-hatched nestlings enjoying substantial advantages compared to last-hatched nestlings. We used this opportunity to test for a trade-off between growth and self-maintenance processes (oxidative stress, telomere erosion) in great tit nestlings, since resource availability and allocation are likely to differ between first-hatched and last-hatched nestlings. We found that despite their starting competitive handicap (i.e. being smaller/lighter before day 16), last-hatched nestlings exhibited growth rate and mass/size at fledging similar to first-hatched ones. However, last-hatched nestlings suffered more in terms of oxidative stress, and ended growth with shorter telomeres than first-hatched ones. Interestingly, growth rate was positively related to plasma antioxidant capacity and early life telomere length (i.e. at 7 days old), but among last-hatched nestlings, those exhibiting the faster body size growth were also those exhibiting the greatest telomere erosion. Last-hatched nestlings exhibited elevated levels of plasma testosterone (T), but only at day 7. T levels were positively associated with oxidative damage levels and plasma antioxidant capacity, the latter being only significant for first-hatched nestlings. Our results suggest that last-hatched nestlings present a specific trade-off between growth rate and self-maintenance processes, which is possibly driven by their need to compete with their older siblings and potentially mediated by elevated levels of T.
authors: GECCO (Groupe écologie et conservation des vertébrés), University of Angers, Angers, France. antoine.stier@gmail.com.
authors: Antoine
authors: A
authors: Stier
authors: IPHC, Université de Strasbourg, 23 rue Becquerel, 67087, Strasbourg Cedex 2, France.|UMR7178, CNRS, 67087, Strasbourg, France.
authors: Sylvie
authors: S
authors: Massemin
authors: IPHC, Université de Strasbourg, 23 rue Becquerel, 67087, Strasbourg Cedex 2, France.|UMR7178, CNRS, 67087, Strasbourg, France.
authors: Sandrine
authors: S
authors: Zahn
authors: IPHC, Université de Strasbourg, 23 rue Becquerel, 67087, Strasbourg Cedex 2, France.|UMR7178, CNRS, 67087, Strasbourg, France.
authors: Mathilde L
authors: ML
authors: Tissier
authors: IPHC, Université de Strasbourg, 23 rue Becquerel, 67087, Strasbourg Cedex 2, France.|UMR7178, CNRS, 67087, Strasbourg, France.
authors: François
authors: F
authors: Criscuolo
mesh_terms: D000375:Aging; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D049628:Body Size / Q000502:physiology*; D005260:Female; D008297:Male; D009425:Nesting Behavior / Q000502:physiology; D018384:Oxidative Stress; D046109:Passeriformes / Q000097:blood / Q000254:growth & development*; D017382:Reactive Oxygen Species / Q000097:blood; D016615:Telomere / Q000502:physiology*; D013739:Testosterone / Q000097:blood
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D013739:Testosterone
keywords: Antioxidant; Intra-brood competition; Oxidative damage; Self-maintenance; Testosterone; Trade-off