Maintenance protocol for the selection regimes. All the populations are maintained under 25°C, ~60% RH, 12 h:12 h Light/Dark cycle on standard cornmeal-molasses-Yeast media in 14-day discrete generation cycles. Larval density is controlled at approximately 150 per vial (8-10 ml of media). On 10th day post egg collection, adults are collected (using CO2 anaesthesia) and held as virgins (8 per vial). Two days later adults are combined in ‘yeasted’ vials in the sex ratio corresponding to the respective selection regime. After two days of interaction period, flies are transferred to fresh food vials for oviposition and allowed an oviposition window of ~18 hours. Following the oviposition window, flies are discarded and the egg density in the vials is controlled to start the next generation.