Genetics of life history in Drosophila melanogaster. II. Exploratory selection experiments.

two types of small-scale selection experiments were performed. (1) Artificial selection experiments were performed on age-specific female fecundity. Selection for early fecundity over three generations produced a statistically detectable direct response. There was no detectable indirect response in other life-history characters. Selection for late fecundity over three generations did not produce any detectable direct response. Indirect responses were detected: early egg-laying decreased and longevity increased. (2) Natural selection for late-age fitness components increased late fecundity, female longevity, and the duration of female reproduction, while early fecundity and mean egg-laying rate decreased.