Temperature experienced during incubation affects antioxidant capacity but not oxidative damage in hatchling...

Our understanding of how oxidative stress resistance phenotypes are affected by the developmental environment is limited. One component of the developmental environment, which is likely central to early life oxidative stress among ectothermic and oviparous species, is that of temperature. We investigated how incubation temperature manipulations affect oxidative damage and total antioxidant capacity (TAC) in red-eared slider turtle (Trachemys scripta elegans) hatchlings. First, to determine whether temperature fluctuations elicit oxidative stress, eggs from clutches were randomly assigned to either a constant (29.5 °C) or daily fluctuating temperature incubation (28.7 ± 3 °C) treatment. Second, to assess the effect of temperature fluctuation frequency on oxidative stress, eggs were incubated in one of three fluctuating incubation regimes: 28.7 ± 3 °C fluctuations every 12 h (hyper), 24 h (normal) or 48 h (hypo). Third, we tested the influence of average incubation temperature by incubating eggs in a daily fluctuating incubation temperature regime with a mean temperature of 26.5 °C (low), 27.1 °C (medium) or 27.7 °C (high). Although the accumulation of oxidative damage in hatchlings was unaffected by any thermal manipulation, TAC was affected by both temperature fluctuation frequency and average incubation temperature. Individuals incubated with a low frequency of temperature fluctuations had reduced TAC, while incubation at a lower average temperature was associated with enhanced TAC. These results indicate that although sufficient to prevent oxidative damage, TAC is influenced by developmental thermal environments, potentially because of temperature-mediated changes in metabolic rate. The observed differences in TAC may have important future consequences for hatchling fitness and overwinter survival.