Genotype-environment interaction for quantitative trait loci affecting life span in Drosophila melanogaster

The nature of genetic variation for Drosophila longevity in a population of recombinant inbred lines was investigated by estimating quantitative genet ic parameters and mapping quantitative trait loci (QTL) for adult life span in five environments: standard culture conditions, high and low temperatur e, and heat-shock and starvation stress. There was highly significant genet ic variation for life span within each sex and environment. In the analysis of variance of life span pooled over sexes and environments, however, the significant genetic variation appeared in the genotype X sex and genotype X environment interaction re rms. The genetic correlation of longevity acros s the sexes and environments was not significantly different from zero in t hese lines. We estimated map positions and effects of QTL affecting life sp an by linkage to highly polymorphic roo transposable element markers, using a multiple-trait composite interval mapping procedure. X minimum of 17 QTL were detected; all were sex and/or environment-specific. Ten of the QTL ha d sexually antagonistic or antagonistic pleiotropic effects in different en vironments. These data provide support for the pleiotropy theory of senesce nce and the hypothesis that variation for longevity might be maintained by opposing selection pressures in males and females and variable environments . Further work is necessary to assess the generality of these results, usin g different strains, to determine heterozygous effects and to map the life span QTL to the level of generic loci.