SELECTION FOR INCREASED LONGEVITY IN DROSOPHILA-MELANOGASTER - A NEW INTERPRETATION

The study of the genetic determinism of longevity in Drosophila melano gaster has made use of the technique of late-age reproduction. At low larval density, that indirect selection showed no effect. At high larv al density, however, increased mean life-span in lines reproduced at l ate age was observed. When these last data are examined as a function of the number of days after the beginning of the experiment, instead o f as a function of generations, the difference in life-span between ea rly and late lines at high larval density disappears. The erratic evol utions of mean longevities in all the experiments here described may b e attributed to unexplained variations in life-span previously observe d in a 4-year experiment. Considering the time lag between the measure ment of a given generation in early and late lines, the experiments of reproduction at late age cannot demonstrate the genetic determinism o f longevity.