Reversal of a female preference after visual exposure to a predator in the guppy, Poecilia reticulata

To test the hypothesis that female choice has been subject to direct selection by predators, it was investigated whether female guppies would switch their choice of mate from more to less conspicuous males after observing a potential predator. Social and sexual preferences of virgin females for each of two males differing in amount of carotenoid pigmentation (an ornamental trait) were measured both before and after visual exposure to a novel predatory cichlid. Females initially showed strong social and sexual preferences for the brighter of the two males. Preferred males also showed lower levels of fluctuating asymmetry in the area of carotenoid pigmentation and displayed at higher rates. After exposure to the cichlid, almost half of the females became sexually unreceptive, and the remainder showed a nearly unanimous sexual preference for the duller male. Control females that did not see the cichlid continued to prefer the brighter male. These results imply that predators have selected against females that mate with conspicuous males. They also suggest that predators can influence sexual selection on male ornaments proximately through their effects on female choice as well as by imposing mortality on conspicuous males. Both conclusions suggest that indirect selection on female preferences may not play a dominant role in this system. (C) 1996 The Association for the Study of Animal Behaviour