Acoustic signals are a vital element of animal communication and sympatric species may use private frequency bands to facilitate intraspecific communication and identification of conspecifics (acoustic communication hypothesis, ACH).
Both, ecological factors associated with partitioning of dietary resources [23] and a selection pressure for maintaining 'private frequency bands' for communication by echolocation ('acoustic communication hypothesis'; [17], [21] have been proposed to explain these deviations from allometry.
R. euryale, who's frequency band is completely encompassed within the broader R. mehelyi band (compare Fig. 1), showed a decreased ability of discriminating conspecifics calls from R. mehelyi calls, which lends some support to the 'acoustic communication hypothesis'.
Under the global communication hypothesis, I expected the large group to emit more vocalisations than the small one.
Among sympatric species call divergence may have evolved under regimes of social selection where character displacement maintains private bandwidths for intraspecific communication (Acoustic Communication Hypothesis [ 48, 67, 75]).
Thus, our results partially support the selection for communication hypothesis, where a strengthened learning ability should help the skill of reading human communicative behaviors.
In contrast, the key concepts of the local communication hypothesis are diffusion, steady state and signalling, i.e. terms related to an underlying mechanism, borrowed from physicochemistry and information technology.
This is described by the gut-brain communication hypothesis, and it is possible that the gut microbiota have a role in the pathogenesis of psychiatric disorders such as depression, particularly when linked to conditions such as IBD [ 74].
Even though the presence or absence of congeneric species may also influence RF variation across different populations of horseshoe bats, we were unable to explicitly test the Acoustic Communication Hypothesis for several reasons.
However, the closest known roosts of these two species are 40 km apart and it is not known if the foraging areas of these two species overlap, i.e. if they are syntopic, as required by the Acoustic Communication Hypothesis.
