How do physiological responses to stress translate into ecological and evolutionary processes?

Identifying physiological adaptation (or absence of it, which we define as stress) to environmental variables requires an explicit link with effects on Darwinian fitness. This can be effected by simultaneous observations on physiological and fitness variables; but the relationships are likely to be complex. Specific hypotheses on functional links between physiology and fitness need to be formulated (and incorporated into models) and tested. The genetic basis of these relationships and the possibility of evolution of tolerance need to be considered. (C) 1998 Elsevier Science Inc. All rights reserved.