Fig. 9.

Genetic background is a significant factor in the dispersal of Drosophila from food. The figure shows the dispersal rates of the natural isolate (NI, solid) used throughout this report and Canton-S (CS, dashed) from chambers that contained a patch of food (red, 65 μL on 2 mL of 0.5% agar) and chambers containing only water (blue, 2 mL of 0.5% agar). From food, the mean dispersal rates were greater than 1 exit per hour for the NI by the third hour (open diamond) and did not exceed this level until the ninth hour for CS (open square). For the first hour, groups of the NI dispersed at a higher rate than groups of CS from water (asterisks). The gray rectangles indicate subjective dawn and dusk. We started experiments 1 h after introducing flies (arrowhead) into chambers, allowing the flies time to settle