Predator exposure alters female mate choice in the green swordtail

Abstract

Female green swordtails, Xiphophorus helleri, show a mating preference for males with brightly colored, elongated swords. This preference is thought to be due to a preexisting receiver bias favoring longer sworded males. In this study, we examined variation in the expression of this sword bias in females. Specifically, we tested the hypothesis that an increase in perceived predation risk will decrease female response to males with longer swords. We used a video playback experiment to evaluate female choice between two recordings of a displaying male that differed only in sword length. We scored responses of females to these recordings immediately before and after they had been exposed to a video recording of a predation event between a cichlid and a male possessing a long sword. We found that prior to exposure to this predation event, females preferred the male with the longer sword. However, after exposure to the predator, females altered their mating response, preferring the male with the sword removed. Exposure to the predator also caused an increase in the frequency with which females moved from potential mating positions to a neutral zone. The results presented here suggest that the female preference for males with longer swords can be modulated based on the perceived risk of predation.