The Costly Trade-off Between Immune Response and Enhanced Lifespan in Drosophila Melanogaster

Abstract

The ability to clear infection generally declines with age in all organisms. Despite this pattern, there is extensive, genetically-based variation among individuals in natural populations in their ability to clear infection at different ages. Mounting an immune response is an energetically costly process. Thus, when individuals differ in age-specific immunity, this variation may reflect individual differences in the amount of energy allotted to mounting an immune response with age. This implies that individuals are allocating limited resources to other energetically demanding tasks (e.g., reproduction), and thus producing a trade-off with immune function. In this experiment, genetically based trade-offs between enhanced lifespan and age-specific immunocompetence were examined using the fruit fly, Drosophila melanogaster as a model system.