From molecules to living systems: historical and contemporary issues in oxidative stress and antioxidant ecology

1. Initial work on oxidative stress and antioxidant defences described basic chemical and biochemical properties and processes and applied this information to issues of animal health and husbandry. Seminal experimental investigations on the damaging effects of oxidative stress and the mitigating effects of antioxidant defences were conducted primarily in domesticated organisms. 2. In recent years, ecologists have taken to studying antioxidants and oxidative stress in free-ranging organisms and have integrated principles of oxidative stress into several core evolutionary concepts, such as life-history trade-offs (e.g. survival vs. reproduction), senescence and sexual selection. This initial flurry of studies has provided major advances in our understanding of how antioxidant defences evolve and function. 3. In this overview, it is our goal to provide ecologists with an accessible summary of (i) the biochemical basis and conceptual frameworks behind oxidative stress and antioxidants, (ii) the research questions and hypotheses that are generated by incorporating antioxidants and oxidative stress into models of life-history theory, ageing, mate selection, and honest signalling, and (iii) the trends in the evidence that have emerged from initial studies in these areas. 4. Though much progress has been made on the ecological and evolutionary relevance of antioxidant and oxidative stress physiology, no consensus has emerged regarding the primacy of how oxidative stress challenges or antioxidant limits or values shape organismal life-histories. However, there are many taxonomic biases in studies to date and several ideal environmental systems that are as-of-yet untapped.