The effect of conditioning the medium in DRosophila, in relation to frequency-dependent selection.

In the context of frequency-dependent selection, the effect of conditioning the medium, by the previous culture of larvae of a given strain, on the survival of subsequent larvae of the same or different strains was measured. Six strains were sued, some inbred and some lines selected for low or high sternopleural bristles. The survival of larvae was not significantly less when the food had been conditioned by the same strain rather than by another strain, nor did conditioning by one strain have any special effect on the survival of another. The survival of lines on medium conditioned by the same strain was not less than on fresh medium, and in some cases was significantly greater.