For Better or Worse: How Early Life Oxidative Stress Moulds the Phenotype

The early environment in which an individual grows up and develops has profound, long-lasting, and often irreversible consequences for the phenotype throughout the individual lifetime. Identifying the physiological mechanisms that orchestrate the phenotypic development and mediate the trade-offs that occur early in life is critical for our understanding of how the diversity in growth and developmental strategies evolves. It is also important to explain why a strategy may be more successful under certain environmental circumstances than others, and also to determine how the individual oxidative status itself is moulded by early experiences. In this chapter, I have discussed (1) the role of maternal effects in moulding the oxidative status of their progeny and (2) how reactive oxygen species organise the phenotypic development. I have also illustrated the role of oxidative stress as both a constraint on and a cost of growth, and how the passive antioxidant protection transferred by mothers to their progeny through the egg, the placenta, or the milk interacts with the maturation of the endogenous antioxidant machinery in determining the organismal capacity to cope with oxidative stress. Finally, I have examined how hormetic priming early in life contributes to build phenotypic resistance to the many challenges of life.