Figure 1

Schematic representation of the selection protocol. The selection was carried out under 12:12 hr LD cycles ("lights-on" at 08:00 and "lights-off" at 20:00 hr). Baseline populations (baseline _1..4 ), maintained for several generations under LD cycles were used to derive four early (early _1..4 ) and four late (late _1..4 ) populations by imposing selection on the timing of adult emergence. Four control populations (control _1..4 ) were also derived simultaneously from the baseline populations, which did not experience any conscious selection pressure. Flies emerging during the morning hours (05:00–09:00 hr) were used to create the early populations, those emerging during the evening hours (17:00–21:00 hr) were used to create the late populations, while flies emerging through out the day were used to raise the controls.