Oxidative stress and the evolution of sex differences in lifespan and ageing in the decorated cricket, Gryllodes sigillatus

The Free Radical Theory of Ageing (FRTA) predicts that oxidative stress, induced when levels of reactive oxygen species exceed the capacity of antioxidant defences, causes ageing. Recently, it has also been argued that oxidative damage may mediate important life-history trade-offs. Here, we use inbred lines of the decorated cricket, Gryllodes sigillatus, to estimate the genetic (co)variance between age-dependent reproductive effort, lifespan, ageing, oxidative damage and total antioxidant capacity within and between the sexes. The FRTA predicts that oxidative damage should accumulate with age and negatively correlate with lifespan. We find that protein oxidation is greater in the shorter lived sex (females) and negatively genetically correlated with lifespan in both sexes. However, oxidative damage did not accumulate with age in either sex. Previously we have shown antagonistic pleiotropy between the genes for early life reproductive effort and ageing rate in both sexes, although this w...