MALE MATE CHOICE AND FEMALE FEMALE COMPETITION FOR MATES IN THE PIPEFISH NEROPHIS-OPHIDION

Male mate choice and female-female competition for access to mates were studied in the pipefish Nerophis ophidion, with the aim of evaluating the function and importance of female size and ornamental skin folds. Nerophis ophidion is sex role-reversed in the sense that paternal care limits female reproductive success. Furthermore, females are larger, possess a sexual coloration, and develop an ornamental skin fold during the spawning season. Females are also more active than males during courtship. In mate-choice experiments males actively preferred both larger females and females with larger skin folds. When several females were kept together, only one female in each group developed a large skin fold. Females interacting only with males invariably developed skin folds whereas isolated females did not. The skin fold affects choice of females by males, and since females are socially stimulated to develop their skin fold, interaction with conspecifics indirectly affects male mate choice. Female-female interactions may suppress the development of the skin fold. Hence, both active male mate choice based upon female secondary sexual characters and female-female interactions determine the non-random mating pattern observed. © 1990 The Association for the Study of Animal Behaviour.