Sexual Dimorphism of Mate Location in the Long-Toed Salamander Ambystoma macrodactylum columbianum

In breeding systems characterized by scramble competition among males, theory predicts that the efficient location of mating partners is more important to males than to females as a component of mating success. We experimentally tested in the laboratory the hypothesis that breeding male long-toed salamanders ( Ambystoma macrodactylum columbianum ), which scramble for mating opportunities, are better able to recognize and locate potential mates than are breeding females. Males were more likely to enter traps containing females than empty traps or traps containing males. Traps containing sponges soiled by females were more likely to attract males than traps containing clean (control) sponges, suggesting that chemical cues may be sufficient for mate location by males. Females were no more likely to enter traps containing males than empty traps. Our results are consistent with the theoretical prediction that selection has been stronger on male long-toed salamanders than on females in the context of capacity for recognizing and locating potential mating partners.