Successful selection for increased longevity in Drosophila: analysis of the survival data and presentation of a hypothesis on the genetic regulation of longevity.

Long lived strains of Drosophila melanogaster have been generated via 25 generations of artificial selection. The mean and the maximum lifespans have been increased both absolutely as well as relative to the controls. The mean lifespan of the selected line now exceeds the maximum lifespan of the controls. The data shows that this increase is entirely accounted for by a genetically based delay in the onset of senescence. Identification and analysis of biomarker data involving reproductive functions supports this interpretation and leads to a suggestion of the processes involved in the lifespan extension. This increase in the duration of the pre-senescent period is under both genetic and environmental control. Senescence itself is not under genetic control and appears to occur stochastically. Selection for decreased longevity was unsuccessful, supporting the concept of a minimum species specific lifespan. A testable hypothesis regarding the biphasic mode of gene regulation of senescence is presented in which a gene-environment interaction takes place in larval life that results in a temporal reprogramming of other, presumably structural, genes which act in adult life at a time prior to the onset of senescence.