Reproductive activities can impose fitness costs as well as benefits. In most anuran species, males clasp females for prolonged periods prior to gamete release, and intuition suggests that the male's presence may impair the female's ability to move about and to feed. We tested the prediction that female locomotion and feeding would be reduced during amplexus in laboratory experiments with Cane Toads, Bufo marinus. Amplexus reduced the female's locomotor (sprint and swim) performance, with the degree of locomotor impairment (speed and distance per hop) dependent upon the body size of the amplectant male for trials of terrestrial locomotion, but not for aquatic locomotion. Amplexus also reduced feeding rates in females; amplectant males did not feed at all. Overall, our data confirm that amplexus imposes locomotor and feeding costs to female Cane Toads, and suggest that this distinctive posture may generate sexual conflict in at least some anuran species.

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