The relationship between longevity and diet is genotype dependent and sensitive to desiccation in <i>Drosophila melanogaster</i>
Andrew W McCracken, E. R. Buckle, Mirre J. P. Simons
Abstract
Dietary restriction (DR) is a key focus in ageing research. Specific conditions and genotypes were recently found to negate lifespan extension by DR, questioning its universal relevance. However, the concept of dietary reaction norms explains why DR's effects might be obscured in some situations. We tested the importance of dietary reaction norms by measuring longevity and fecundity on five diets in five genotypes, with and without water supplementation in female Drosophila melanogaster (N&gt;25,000). We found substantial genetic variation in the response of lifespan to diet. Flies supplemented with water rescued putative desiccation stress at the richest diets, suggesting water availability can be an experimental confound. Fecundity declined at these richest diets, but was unaffected by water, and this reduction is thus most likely caused by nutritional toxicity. Our results demonstrate empirically that a range of diets need to be considered to conclude an absence of the DR longevity effect.