The influence of the acoustic community on songs of birds in a neotropical rain forest

Species interactions and the structure of complex communication networks

“…Specifically, they indicate that the dominant mechanisms structuring such networks can lead to stereotypy and synchrony among species, generating a pattern of clustering in traits and behaviors, thereby helping to explain why so many studies of multispecies choruses have found the signature of partitioning to be weak (6,7,15,30) or absent (8,17).…”

“…O ne of the core principles of animal communication is that signals should be detectable and convey an accurate message against a noisy background (1-3). This background can involve direct overlap of sounds, as in the case of masking by simultaneous signals (4,5), or simply the co-occurrence of different species using confusingly similar signals at the same location (6)(7)(8). As most animals communicate within assemblages of related species, the problem of signal interference is widespread and may have far-reaching implications for the evolution of signals and signaling behavior.…”

“…Conversely, species cooccurring at local scales may be less divergent because they are segregated by habitat across a study site and therefore are unlikely to signal together. Although some studies (7,11) partially overcome these issues by sampling assemblages from single points in space, none has considered the effects of habitat and the potential role of competitive interactions among related species (16). Moreover, previous studies have generally assessed partitioning in relatively small assemblages (<30 species), reducing both the likelihood of competition over transmission optima and the power of statistical tests.…”

“…Finally, many tropical species are permanently resident and apparently interspecifically territorial, using acoustic signals to mediate competitive interactions with heterospecifics (18,26,29). In combination, these factors imply that large numbers of species compete both for ecological resources and a narrow window of optimal signaling space (7,30), providing a context in which to test the relative importance of acoustic partitioning and interspecific communication networks.…”

Songs of Darwin's finches diverge when a new species enters the community

“…Finches arriving at an island may encounter both a different habitat and a different constellation of species. The presence of congeneric species could select for divergence in song if there is a fitness penalty to interbreeding (16,29) or more generally if there is a communication benefit from minimizing acoustical interference (30)(31)(32). Peak shift, a learning phenomenon whereby an individual responds more to an exaggerated form of its own signal in a direction away from a congeneric signal, is a mechanism that would lead to divergence between songs of related species as a consequence of direct social interactions (33-35).…”