Abstract
Signals are basic blocks that constitute the communication, and the combination of the emission of signals and the responses to them comprise the communication process. The acoustic communication has a key role in the life history of anurans because it is used to mediate social interactions, influences the risk of predation and parasitism, and is directly linked to reproductive success. However, species that inhabit acoustically complex environments, such as streams, face an ecological problem that may hamper acoustic communication: the noise produced by stream torrents. The visual communication has evolved independently in several families of diurnal stream frogs, probably to supplement or to replace the acoustic signals due to the interference of the environmental noise. It has also been found that some of these species use multimodal displays characterized by the association between visual and acoustic signals. Depending on the type of selective pressure acting on signals, the multimodal display may have evolved to accomplish different functions. Furthermore, besides having long-term adaptations, such as visual and multimodal signals, some frogs may temporarily adjust call traits in order to minimize the effect of noise on acoustic communication. However, the knowledge on the function of multimodal displays and the effect of environment noise on the reproductive success of stream frogs is still very incipient, particularly for diurnal frogs from the Neotropics. This project aims to test hypotheses about the functional significance of multimodal displays, and about the effects of environmental factors on the reproductive success of the frog Crossodactylus schmidti (Hylodidae), a species that has been used as a good model for studies about communication of diurnal frogs from Neotropical streams. Our innovative experimental approach will use electromechanical models in field. The results obtained here will bring relevant information on the functional significance of multimodal displays in stream frogs. Moreover, this will be one of the first studies to investigate the effect of environmental noise on the mating success of an anuran species.Key-words: acoustic niche, communication, complex displays, Crossodactylus, sexual selection, signal-noise relationship.
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