Oxidative status and telomere length in a long-lived bird facing a costly reproductive event

Abstract

Summary1. Life-history theory predicts that high reproductive investment alters self-maintenance. Several mechanisms underlying the cost of reproduction have been previously suggested, but how parental effort may impact cell and organism maintenance remains largely unknown. The effects of oxidative stress -the imbalance between oxidative damage and defences -on telomere dynamics may underlie this relationship. Indeed, oxidative stress is associated with costly activities like breeding, and impacts telomere length that is known to predict survival in birds. According to life-history theory, long-lived species are expected to minimize the adverse effects of current reproduction on their body maintenance and should therefore enhance their antioxidant capacity and preserve their telomeres when breeding workload increases. 2. In this study, we tested this hypothesis by determining experimentally how the oxidative status and telomere length were modified when long-lived Ade´lie penguins (Pygoscelis adeliae) faced a costly reproductive event. The breeding workload was increased through a handicapping procedure that increased the cost of foraging and therefore chick-provisioning. 3. In agreement with our hypothesis, Ade´lie penguins substantially increased their antioxidant defences during a costly breeding effort, while oxidative damage and telomere length remained unchanged. 4. As expected in long-lived species, Ade´lie penguins subjected to increased breeding constraints appear to prioritize self-maintenance as shown by their increased antioxidant capacity. Moreover, the absence of effects of our experimental procedure on telomere length suggests no apparent impact of breeding workload on the senescence of this long-lived bird. However, to better understand the role of the couple 'oxidative status ⁄ telomeres' in the regulation of life-history strategies, further studies should examine: (i) the nature and the cost of additional antioxidant protection; (ii) the changes in the oxidative status of animals throughout their annual cycle and the consequences on telomere dynamics; and (iii) the repartition of antioxidant resources between young and parents.

Telomere length reflects phenotypic quality and costs of reproduction in a long-lived seabird

“…However, Beaulieu et al [54] did not detect a significant difference in telomere shortening between individuals providing differential reproductive effort in free-living Adélie penguins (Pygoscelis adeliae), induced by handicapping, and thus presumably increasing foraging costs. Further experimental work, manipulating reproductive effort, is required to establish whether there is a causal effect of reproductive effort on telomere shortening in birds.…”

The role of the antioxidant system during intense endurance exercise: lessons from migrating birds

“…2), which can be measured in the circulation (Tsahar et al, 2006). As such, uric acid largely determines the total antioxidant capacity of serum (Cohen and McGraw, 2009), although non-enzymatic antioxidant capacity measured by the OXY adsorbent test does not include uric acid (Beaulieu et al, 2011). Measuring uric acid in addition to performing the OXY adsorbent test therefore provides a means to determine the importance of uric acid relative to other nonenzymatic antioxidant defenses.…”

“…Beaulieu et al, 2011Jenni-Eiermann et al, 2014;Speakman, 2008;Tsahar et al, 2006). The regulation of oxidative damage may act as an underlying driver of aging or longevity (Montgomery et al, 2012;Selman et al, 2012).…”

Bill size correlates with telomere length in male American Redstarts

“…Telomeres appear to shorten throughout the life of individuals (Pauliny et al 2006;Bize et al 2009;Salomons et al 2009;Heidinger et al 2012;Angelier et al 2013;Barrett et al 2013;Bauch et al 2013;Boonekamp et al 2014) and, importantly, telomere length (TL) has been shown to be a reliable predictor of survival under some circumstances (Haussmann et al 2005;Pauliny et al 2006;Bize et al 2009;Salomons et al 2009;Heidinger et al 2012;Angelier et al 2013;Barrett et al 2013) but not others (Pauliny et al 2006;Beaulieu et al 2011;Caprioli et al 2013;Boonekamp et al 2014). Therefore, specific attention has been paid to the determinants of TL in wild vertebrates.…”