Effects of forced copulations on female sexual attractiveness in fruit flies

Keywords: courtship Drosophila melanogaster forced copulation fruit fly sexual behaviour sexual conflict Male fruit flies (Drosophila melanogaster) force-copulate with females during the females' short vulnerable period following eclosion. Although sexually immature at that time, the females produce viable progeny from forced copulations. While the females could gain fitness from remating with their chosen male when reaching sexual maturity, mating in female fruit flies is typically followed by a long period of reduced attractiveness and receptivity. To test whether forcibly mated females can overcome the typical effects of mating, we quantified the effects of consensual versus forced matings on female attractiveness and receptivity. Forcibly mated females were as attractive to males as same-age virgin females and more attractive than consensually mated females. The forcibly mated females, however, remated at lower frequencies than same-age virgin females but at higher frequencies than consensually mated females. Our results suggest an intriguing outcome of sexual conflict in which males can sire offspring with and reduce the receptivity of forcibly mated females, but these females can retain their attractiveness and partial receptivity to males. In most animals, many more males than females seek mates at any given time. One outcome of the consequent sexual conflict between the sexes is that males attempt to forcibly copulate with Forced copulations have not been well studied in spite of their potential importance for the evolution of mating systems and sexual selection. We recently substantiated Markow's (2000) observations of forced copulations in wild fruit flies (D. melanogaster and D. simulans) in Arizona, U.S.A., by quantifying forced matings in wild as well as laboratory populations of D. melanogaster. Male fruit flies vigorously courted newly eclosed females, which ran away from the males, kicked them and attempted to dislodge mounting males. The males, however, succeeded in mating in about 20% of the encounters (Seeley & Dukas 2011). Forcibly mated females had reduced longevity, higher rates of wing damage and fewer progeny than consensually mated females (Dukas & Jongsma 2012). The data on forced copulation in fruit flies open up opportunities for a detailed examination of the evolution of and mechanisms underlying this extreme form of sexual conflict. In the variety of birds, mammals and insects in which forced copulations have been studied, females mate often and with more than one male In D. melanogaster as well as many other insects, however, females typically become unreceptive and unattractive to males for a long …