For behavioral testing, 25 virgins and males were mated for 2 days in bottles with 50 ml standard media with a few added grains of Baker’s yeast, and groups of 20 to 25 young adult male progeny were collected into standard food vials without yeast 11 days later. Flies were allowed to recover from CO2 anesthesia for 2 days and were tested behaviorally between 11 am and 6 pm. Behavioral tests were carried out at 25°C with constant illumination. Each experiment consisted of a group of 20 to 25 genetically identical flies that were progeny from 1 parental cross. Replicate experiments were carried out with groups collected from distinct parental crosses and were carried out on different days. This design was used to take day-to-day and potential genetic variation into account. Ethanol was delivered as a continuous vapor stream that was mixed with a humidified air stream to achieve a flow rate of 5.5 l/min. Ethanol concentration is expressed as the percentage of ethanol vapor: [(ethanol vapor)/(ethanol vapor + humidified air)] × 100. Behavioral experiments were performed in the 8
