Does reproduction cause oxidative stress? An open question

There has been substantial recent interest in the possible role of oxidative stress as a mechanism underlying life-history trade-offs, particularly with regard to reproductive costs. Several recent papers have found no evidence that reproduction increases oxidative damage and so have questioned the basis of the hypothesis that oxidative damage mediates the reproduction–lifespan trade-off. However, we suggest here that the absence of the predicted relationships could be due to a fundamental problem in the design of all of the published empirical studies, namely a failure to manipulate reproductive effort. We conclude by suggesting experimental approaches that might provide a more conclusive test of the hypothesis.

► It has been hypothesised that oxidative stress underlies life-history trade-offs.
► However, evidence that reproduction causes oxidative stress is weak.
► We point out that none of the studies to date manipulates reproductive effort.
► This lesson was learned many years ago in studies of the cost of reproduction.
► We suggest experimental approaches that will better test the hypothesis.