female fitness and that drive coevolution between the sexes. The rate of adaptation depends
on the intensity of selection and its efficiency, which depends on drift and genetic variability.
This leads to the largely untested prediction that coevolutionary adaptations such as those
driven by sexual conflict should evolve faster in large populations. We tested this using the
bruchid beetle Callosobruchus maculatus, a species where harm inflicted by males is well …