Phenomenon of life span instability in Drosophila melanogaster: I. Nonrandom origin of life span variations in successive generations.

The dynamics of life span (LS) and fecundity in Drosophila melanogaster, strain D-32, were analyzed in a series of successive generations. Highly reliable variations in both fitness components were found. On initial inspection the variations would be characterized as random or irregular wherein mean values differed up to threefold. The variance in longevity is greater in females than in males. By use of mathematical procedures we have shown a scale regularity in LS distributions for all generations. Such regularity, in spite of considerable differences in absolute values (mean and maximum LS), suggested that the origin of LS instability is nonrandom.