Abstract

Females often have traits that may be useful as indicators of their reproductive status. Female Green Swordtails (Xiphophorus helleri) have a brood patch, a darkened region on their abdomen that is largest prior to parturition. In this field experiment, female Green Swordtails either received a control treatment or their brood patch was augmented with tattoo ink. The females were released sequentially and the number of males approaching and courting each of these females was recorded. The number of males approaching females of the sham and augmented groups was indistinguishable, but significantly more males courted the females with augmented brood patches than the females of the sham group. Male responses to female indicators of reproductive status suggest that males may make evolutionarily important mating decisions due to either time or sperm limitation.