ARTIFICIAL SELECTION FOR DEVELOPMENTAL TIME IN DROSOPHILA-MELANOGASTER IN RELATION TO THE EVOLUTION OF AGING - DIRECT AND CORRELATED RESPONSES

A wild-type strain of Drosophila melanogaster was successfully selecte d for both fast and slow larval development. The realized heritabiliti es (h(2)) ranged from 0.20 to 0.30 for the fast lines and 0.35 to 0.60 for the slow lines. The selection applied is relevant in relation to the evolution of aging. The longevity of adults, either virgin or mate d, was not affected by selection for developmental time, indicating th at developmental time is not a causal determinant of life span, thus c onfirming the results of the studies on environmental effects on aging (Zwaan et al. 1991, 1992). However, adult body weights were higher in the slow developmental lines and lower in the fast lines, relative to the control flies. Furthermore, slow females showed relatively high e arly fecundity and low late fecundity, as compared with control and fa st females. Mated longevities and total lifetime progeny productions w ere not statistically different. Previous results obtained by other au thors from selection experiments on age at reproduction either support ed the mutation accumulation or the negative pleiotropy theory of agin g (Luckinbill et al. 1984; Rose 1984b). The impact of the reported res ults on the interpretation of these studies is discussed, and it is no ted that direct selection on adult longevity is needed to settle this issue.