Male biases for male characteristics in females in Priapella olmecae and Xiphophorus helleri (family Poeciliidae)

Preexisting receiver biases can affect the evolution of sexually selected t raits once traits favored by such biases arise. Female guayacon olmeca, Pri apella olmecae, and green swordtail, Xiphophorus helleri, possess a bias fa voring sworded conspecific males, despite phylogenetic evidence that the se xually selected sword expressed by male swordtails arose in Xiphophorus aft er the divergence of the two genera. In this study, we investigated the sta te of the bias favoring a sword in male Priapella and Xiphophorus to determ ine whether males also possess a bias that could operate in an intersexual selection context. Male P. olmecae preferred conspecific females with sword s to those without swords. Thus, males and females in this unsworded specie s appear to share a preexisting bias favoring individuals of the opposite s ex with swords. Male X. helleri, however, did not express a bias favoring s worded females, instead, in this species in which the sword is restricted t o males, males discriminated against conspecific females with swords. Previ ous work suggests that female mate choice and male-male competition likely contribute to the maintenance of the sword in X. helleri. The sword may als o Flay a role in sex recognition in swordtails. The absence of a sword pref erence in male green swordtails could reflect the current function of the s word.