Early-Life Climbing Stratifies the Metabolome and Mortality Risk in Genetically Identical Flies

Studies in laboratory organisms typically minimize all environmental and genetic variation other than the intervention of interest. In aging studies, these highly controlled conditions have yielded profound insights into aging. But even within isogenic cohorts of lab animals in controlled environments, we observe substantial variation in lifespan. Here we exploited the climbing behavior of Drosophila to study variation in mortality among isogenic populations in a controlled environment. We show that fractionating large cohorts of relatively young isogenic flies by climbing behavior predicts future mortality risk and stress sensitivity. Using metabolomics to dissect this variation, we found metabolites whose abundances differ among the fractions. We also took advantage of the large number of individuals in each fraction, and the ease with which they can be collected, to explore the covariance structure of metabolites in flies that are genetically identical, but divisible into short-lived and long-lived fractions. In doing so, we identified metabolites and metabolic pathways as candidate biomarkers of intrinsic mortality risk.