AbstractFemale ornaments are a rare occurrence in nature. One explanation for this is that female ornaments are costly to produce and maintain and, therefore, females must trade-off resources related to reproduction to promote ornament expression. Here, we investigate the potential trade-off between female ornamentation and fecundity in the sex-role reversed, wide-bodied pipefish, Stigmatopora nigra. We measured two components of the female ornament, body width and stripe thickness, and tested the relationship between these ornaments and female fecundity and the mean egg size. Both body width and stripe thickness were strongly and positively related to female body size. After controlling for the influence of body size, we found no evidence of a cost of belly width or stripe thickness on female fecundity. Rather, females that have larger ornaments have higher fecundity and thus a greater relative fitness advantage. However, larger females suffered a slight decrease in egg size, consistent with a potential trade-off between egg size and body size, although no relationship between egg size and ornaments was observed. Our results suggest that larger S. nigra females accurately advertise their reproductive value to males, and underscore the importance of investigating the potential mechanisms that promote and maintain honesty of female ornaments.
Female ornamentation and the fecundity trade-off in a sex-role reversed pipefish