Sexual selection for sensory exploitation in the frog Physalaemus pustulosus

Area of Science:

• * Evolutionary Biology
• * Animal Behavior
• * Bioacoustics

Background:

• * Female mate preferences are well-documented, often influenced by auditory system properties.
• * Mechanisms driving sexual selection within a population based on sensory traits are less understood.
• * A potential mechanism involves female sensitivity to male signals deviating from the population average.

Purpose of the Study:

• * To investigate how sensory characteristics can drive sexual selection within a population.
• * To test the hypothesis that female sensitivity to male courtship signal deviations influences mate choice.
• * To examine the role of sensory exploitation in the evolution of female mate preferences in Physalaemus pustulosus.

Main Methods:

• * Auditory system analysis of female Physalaemus pustulosus.
• * Acoustic analysis of male Physalaemus pustulosus courtship calls, focusing on the 'chuck' component.
• * Comparative analysis of female auditory tuning between Physalaemus pustulosus and Physalaemus coloradorum.

Main Results:

• * Female Physalaemus pustulosus basilar papilla tuning is biased towards lower frequencies within the male 'chuck' call.
• * This tuning explains the preference for lower-frequency chucks, which are produced by larger males.
• * Female auditory tuning did not differ between P. pustulosus and P. coloradorum, indicating pre-existing preference evolution.

Conclusions:

• * Female preference for lower-frequency chucks in Physalaemus pustulosus is driven by pre-existing sensory biases.
• * The evolution of this preference is attributed to sexual selection via sensory exploitation, not runaway or natural selection.
• * Sensory exploitation provides a novel framework for understanding the evolution of sexual selection within populations.