Behaviour 2019
Acoustic allometry in rheophilic frogs and insights on the loss of advertisement call in Megaelosia
Guilherme Augusto-Alves1,2, Simone Dena3, Luís Felipe Toledo2,3. 1Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Unicamp, Campinas, São Paulo, Brazil; 2Programa de Pós-Graduação em Ecologia, Instituto de Biologia, Universidade Estadual de Campinas (Unicamp), Campinas, São Paulo, Brazil; 3Fonoteca Neotropical Jacques Vielliard (FNJV), Museu de Zoologia Adão José Cardoso (ZUEC), Instituto de Biologia, Unicamp, Campinas, São Paulo, Brazil

Most of the anuran species communicate through sounds. Species that inhabit rivers and streams need to deal with the low-pitched noise produced by water flow. Since this noise can interfere with communication, natural selection may favor individuals who produce high-pitched calls or alternative signals in these locations. However, there is a limit imposed by their body size, as larger frogs tend to have lower frequency calls. We evaluated acoustic allometry in species of four genera of Atlantic Forest frogs that call in noisy habitats (Hylodes, Crossodactylus, and Cycloramphus) or in quieter rocky walls (Thoropa). We found allometric relationships for Hylodes and Thoropa, but did not find allometry for Crossodactylus and Cycloramphus spp.. Also, expanding the allometric relation from Hylodes to Megaelosia (sister group) it is possible to explain the relationship between environmental noise and the muteness in this genus. As these frogs have large body sizes, they would call with frequencies so low that it would be masked by the noise. We provide information that extends the known influence of the background rivers and streams noise to a phenotypic constrainer.