Phenotypic plasticity is wide-spread in animals, but how plastic responses to predation threat affect traits under sexual selection and influence mating preferences is not well understood. Here, we examined how chronic predation risk during development and acute predation risk during mate choice affect the expression of male secondary sexual traits and female mating preference in the three-spined stickleback, Gasterosteus aculeatus. Males reared under chronic predation risk developed less intense red breeding colouration but showed higher...