The effects of population size and selection intensity in selection for a quantitative character inDrosophila: I. Short-term response to selection

Abstract

1. The response to selection for increased number of bristles on one abdominal segment was studied over 12 generations using a factorial design of three population sizes (10, 20 and 40 pairs of parents) and five selection intensities (10, 20, 40, 80% and controls).2. The responses on the average agreed well with those expected from the estimated base population heritability, but individual replicates diverged considerably.3. Larger populations tended to give greater response to selection, due mainly to larger realized heritabilities.4. There was no consistent effect of selection intensity on realized heritability.5. For populations with the same number of individuals scored, less intense selection gave greater realized heritabilities.