Habitat use mediates the conflict of interest between the sexes

Males of many species have alternative mating behaviours and must make decisions about which behaviours to use to maximize reproductive success. Guppies, Poecilia reticulata, have two alternative mating behaviours: display behaviour, which facilitates female choice, and sneak mating, a form of sexual coercion, which circumvents female choice. The choice of which behaviour to use and the circumstances in which behaviours are used can be potentially costly to both sexes. We examined the influence of variation in water velocity on male mating behaviour in nature and in controlled laboratory conditions in which we were able to control for male size. We first examined whether males use alternative behaviour when subjected to changes in water velocity and then whether females have the potential to ameliorate male harassment by moving to high water velocities where the smaller males may be excluded. Females preferentially used higher available water velocities than males and mating activity decreased with increasing water velocity. However, at high water velocities males switched from displays to sneak mating behaviour, the behaviour type that most opposes female interests. Females thus have the potential to reduce, but not entirely escape, the detrimental effects of this sexual conflict by moving to high water velocities.