How Do Animals Adapt to Chronic Heat

Among the various physical environmental stressors, “temperature is ecologically most important, for it is a factor that is all pervasive, and in most environments, lacks spatial or temporal constancy” (Cossins and Bowler, 1987). Concomitantly, upon transfer from one temperature to another for prolonged periods, most animals can adapt physiologically and biochemically to the new environment. This process is termed thermal acclimatization/ acclimation and, if successful, such adaptation enhances thermal tolerance in terms of the extreme of tolerable temperature and the duration of endurance in that temperature (Horowitz, 1998). Although time is required to develop acclimation, the acclimation effect is long acting. Acclimation is a “within life time mechanism”, reversible, and may involve a genetic basis, although not necessarily. We suggest that such a widespread event, which gives rise to a new phenotype, comprises a reprogramming of gene expression and translational processes. In this presentation, the mechanisms underpinning the phenotypic transition in response to persistent exposure to a hot environment (heat acclimation) and the beneficial outcomes are discussed.