BEE, M. A.; MARSHALL, V. T.; HUMFELD, S. C.; GERHARDT, H. C.; Carl von Ossietzky Universit�t, Oldenburg, Germany; Univ. of Missouri, Columbia; Univ. of Missouri, Columbia; Univ. of Missouri, Columbia: The Role of Learning in the Formation of Frog Choruses

Anuran mating behaviors are usually thought to lack the scope for experience-mediated behavioral plasticity common in higher vertebrates. New evidence, however, highlights the importance of short-term and long-term forms of learning in the formation of breeding choruses of frogs. In bullfrogs (Rana catesbeiana, Ranidae), males defend long-term, multi-purpose territories. Repeated exposure to the calls of a simulated new neighbor leads to decreases in territorial aggression that are maintained over long-term retention intervals and specific to both the pitch of the calls and their location of origin. This form of behavioral plasticity allows male bullfrogs to exhibit low levels of aggression toward established neighbors, while maintaining a readiness to respond aggressively to non-territorial intruders. In spring peepers (Pseudacris crucifer, Hylidae), males defend temporary calling sites in breeding aggregations in which the density of calling males is highly variable both temporally and spatially. Repeated exposure to the calls of a simulated new neighbor leads to short-term increases in a male�s threshold for producing aggressive vocalizations, and thresholds return to baseline levels after short retention intervals. This form of behavioral plasticity allows male spring peepers to track fluctuations in the local density of other calling males in a highly variable social environment. Sensory adaptation and effector fatigue can be ruled out as explanations for the behavioral changes seen in both species, indicating that centrally mediated learning processes play an important role in the formation of breeding choruses in these species.