The variability between individuals as a measure of senescence: A study of the number of eggs laid and the percentage of hatched eggs in the case of Drosophila melanogaster

Abstract

Three variables were measured on adult females of Drosophila melanogaster raised at temperatures of 13° and 25°C: longevity, fecundity (number of eggs laid) and fertility (percentage of hatched eggs). Fecundity and fertility decline as the females get older: these physiological changes seem to be the result of aging. For these two characteristics the variability between individuals measured by the coefficient of variation (c.v.) increases exponentially as a function of time. The curves are analogous to those of the mortality rate (Gompertz curves) and appear to be suitable for the measurement of the rate of aging. If this is the case, flies raised at 13°C are distinguished by a higher “initial physiological handicap” (parameter R 0), i.e. low vitality, as well as by slower aging (parameter α).