Royal Society Publishing

Turgid female toads give males the slip: a new mechanism of female mate choice in the Anura

Bas Bruning , Benjamin L. Phillips , Richard Shine

Abstract

In many anuran species, males vocalize to attract females but will grasp any female that comes within reach and retain their hold unless displaced by a rival male. Thus, female anurans may face strong selection to repel unwanted suitors, but no mechanism is known for doing so. We suggest that a defensive trait (the ability to inflate the body to ward off attack) has been co-opted for this role: by inflating their bodies, females are more difficult for males to grasp and hence, it is easier for another male to displace an already amplexed rival. Inflating a model female cane toad (Bufo marinus) strongly reduced a male's ability to maintain amplexus; and females who were experimentally prevented from inflating their bodies experienced no successful takeovers from rival males, in contrast to control females. Thus, the ability of a female cane toad to inflate her body may allow her to manipulate the outcome of male–male competition. This overlooked mechanism of anuran mate choice may reflect a common evolutionary pattern, whereby females co-opt defensive traits for use in sexual selection.

Footnotes

    • Received November 13, 2009.
    • Accepted December 8, 2009.
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