The metabolic cost of multiple environmental stresses: Implications for climatic change and conservation

The evolution of resistance to environmental stress may involve genetic change associated with reduced metabolic energy expenditure. Under the stressful conditions likely at the limits of species' geographical ranges, physiological constraints may mean that the amount of energy required to counteract stress precludes survival. Metabolic limitations would therefore prevent spread into climatically more extreme habitats. This means that postulated future climatic changes are likely to cause species extinctions, especially in species-rich rain forests. Metabolic cost arguments suggest that this situation may be more extreme if there are interactions with other stresses. Conservation genetics should therefore incorporate an analysis of stress-response traits, emphasizing populations from species boundaries.