Antioxidant capacity, lipid peroxidation, and lipid composition changes during long-term and short-term thermal acclimation in Daphnia.

Examples of phenotypic plasticity-the ability of organisms of identical genotypes to produce different phenotypes in response to the environment-are abundant, but often lack data on the causative physiology and biochemistry. Phenotypes associated with increased protection against or reduced damage from harmful environments may, in fact, be downstream effects of hidden adaptive responses that remain elusive to experimental measurement or be obscured by homeostatic or over-compensatory effects. The freshwater zooplankton crustacean Daphnia drastically increases its heat tolerance as the result of acclimation to high temperatures, an effect often assumed to be based on plastic responses allowing better protection against oxidative stress.