Evolução da variação intraespecífica em cantos de anúncio de Allobates sp.

Abstract

The acoustic signals are primordial for communication in a variety of animal groups and they may contain information about the informer’s identity, body size, physical location, species and sexual status even at relatively long distances. If some properties of the acoustic signal is degraded during of their propagation path, the signal lose their effectiveness and cannot fulfill its function. The characteristics of the acoustic signal can be modified due to various environmental effects, mainly related to changes in the structure of the surrounding habitat and background noise consisting of acoustic signals emitted by sympatric organisms conspecific or heterospecific. The Acoustic Adaptation Hypothesis (AAH) suggests that the acoustic communication is adapted to each habitat type, to maximize the transmission distance by minimizing the call attenuation and degradation caused by reverberations. In this paper we evaluate the existence of relations between differentiation into acoustic signals of a species of an Amazonian anuran species (Allobates sp.). The work was conducted in forests along a 600 km, of the interfluve between two large southern tributaries of the Amazon River. Additionally, we searched the acoustic environment across for species that emitted signals that overlapped in bandwidth with those of the focal species. We observed that the acoustic signals of Allobates sp. are shorter and emitted at lower frequencies in forests with higher tree densities and larger tree basal areas, as predicted by AAH. However, signal modulation was not affected by environmental parameters. The presence of a syntopics species that emitted signals with overlapping frequency was not associated with the variation of any acoustic trait of the focal species. Furthermore, our study highlights the importance of representing the structure of the vegetation on several parameters relate to the subtle patterns of variation of acoustic signals.