Key issues in achieving an integrative perspective on stress.

An integrative perspective on molecular mechanisms of stress resistance requires understanding of these mechanisms not just in vitro or in the model organism in the research laboratory - but in the healthy or diseased human in society,in the cultivated plant or animal in agricultural production,and in populations and species in natural communities and ecosystems. Such understanding involves careful attention to the context in which the organism normally undergoes stress,and appreciation that biological phenomena occur at diverse levels of organization (from molecule to ecosystem). Surprisingly,three issues fundamental to achieving an integrative perspective are presently unresolved: (i) Is variation in lower-level traits (nucleotide sequences, genes, gene products) seldom, commonly, or always consequential for stress resistance? (ii) Does environmental stress reduce or enhance genetic variation, which is the raw material of evolution? (iii) Is the present distribution of organisms along natural gradients of stress largely the result of organisms living where they can, or is adaptive evolution generally sufficient to overcome stress? Effective collaboration among disciplinary specialists and meta-analysis may be helpful in resolving these issues.