Department of Biology, The Center for Genomic Advocacy, Indiana State University, Terre Haute, Indiana.
Department of Biology, Behavioural Ecology and Ecophysiology Research Group, University of Antwerp, Wilrijk, Belgium.
J Evol Biol. 2019 Feb;32(2):134-143. doi: 10.1111/jeb.13400. Epub 2018 Dec 3.
A central objective of evolutionary biology is understanding variation in life-history trajectories and the rate of aging, or senescence. Senescence can be affected by trade-offs and behavioural strategies in adults but may also be affected by developmental stress. Developmental stress can accelerate telomere degradation, with long-term longevity and fitness consequences. Little is known regarding whether variation in developmental stress and telomere dynamics contributes to patterns of senescence during adulthood. We investigated this question in the dimorphic white-throated sparrow (Zonotrichia albicollis), a species in which adults of the two morphs exhibit established differences in behavioural strategy and patterns of senescence, and also evaluated the relationship between oxidative stress and telomere length. Tan morph females, which exhibit high levels of unassisted parental care, display faster reproductive senescence than white females, and faster actuarial senescence than all of the other morph-sex classes. We hypothesized that high oxidative stress and telomere attrition in tan female nestlings could contribute to this pattern, since tan females are small and potentially at a competitive disadvantage even as nestlings. Nestlings that were smaller than nest mates had higher oxidative stress, and nestlings with high oxidative stress and fast growth rates displayed shorter telomeres. However, we found no consistent morph-sex differences in oxidative stress or telomere length. Results suggest that oxidative stress and fast growth contribute to developmental telomere attrition, with potential ramifications for adults, but that developmental oxidative stress and telomere dynamics do not account for morph-sex differences in senescence during adulthood.
进化生物学的一个主要目标是理解生命史轨迹和衰老或衰老速度的变化。衰老可能受到成年期的权衡和行为策略的影响，但也可能受到发育压力的影响。发育压力会加速端粒降解，从而对长期寿命和适应度产生影响。关于发育压力和端粒动力学的变化是否会导致成年期衰老模式的变化，我们知之甚少。我们在两性异形的白喉雀（Zonotrichia albicollis）中研究了这个问题，这种雀类的两种形态的成年个体表现出行为策略和衰老模式的明显差异，我们还评估了氧化应激和端粒长度之间的关系。表现出高水平无辅助亲代养育的棕褐色雌性表现出比白色雌性更快的生殖衰老，比所有其他形态-性别类别的个体更快的表型衰老。我们假设棕褐色雌性雏鸟中的高氧化应激和端粒损耗可能导致这种模式，因为棕褐色雌性体型较小，即使在雏鸟期也可能处于竞争劣势。比巢伙伴小的雏鸟具有更高的氧化应激，而具有高氧化应激和快速生长率的雏鸟具有较短的端粒。然而，我们没有发现氧化应激或端粒长度在形态-性别上存在一致的差异。结果表明，氧化应激和快速生长导致了发育中端粒的损耗，这可能对成年个体产生影响，但发育中的氧化应激和端粒动力学并不能解释成年期两性异形衰老模式的差异。
