Understanding phenotypic integration from perspectives of allocation, risk and aging

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A principle underlying how organisms evolve is that investments must be optimally balanced for successful living, but strong investments in one area require reductions in others. Functions (like growth and reproduction) do not simply compete for resources but allocation among them is a hormonally regulated "strategy" that adjusts to the environment. We are studying global regulation of functions using giant transgenic mice because greatly exaggerated growth allows us to see the relationship of other functions to growth and to each other. Of particular interest is the remarkable accelerated aging of these mice. Growth may divert resources from functions that forestall aging (e.g., pathways mediating stress resistance). We are learning more by developing dietary supplements that actually slow the aging rate of mice and insects. These allow us to see how slower aging is achieved. We recently found that insects and crustaceans recognize and avoid injured or dead relatives using particular odours. Such risk avoidance may be applied to control diverse pests. Moreover, crickets exposed to the odour of death not only altered their eyes, wings, and spines, they also lived longer. Food restriction is the only other known way of greatly extending longevity of most animals. However, benefits (including stress resistance) disappear if restricted animals can smell food. Thus, adjustments to risk of death or famine that increase life span both involve smell. Life extension is generally associated with elevated stress resistance so we plan to examine such adjustments in mammals and insects exposed to olfactory signals of death or signals indicating stress or immune activation in others. These studies of functional alterations in response to nutrition and risk have vast implications for how ecological populations and communities function.