| dc.description | Acoustic signals are used for species recognition, mate choice, and resource
defense, but the frequencies used are restricted by body-size, phylogeny,
habitat structure, and biotic and abiotic sounds in the habitat. Acoustic space
is a limited resource, and studies have suggested that species avoid
competition by partitioning this space in time and frequency. Alternatively,
other studies have reported temporal synchrony and spectral overlap among
species. These studies have focused on individual taxonomic groups (e.g. fish,
bird, insects, and anurans), and no study has assessed patterns of acoustic
activity for all species in a community across a gradient of species richness.
Here we compare the use of acoustic space (i.e. soundscape) in nine tropical
forest sites, and show a highly significant positive relationship between the
percent of acoustic space used and total bird, amphibian, and mammal species
richness. If community richness is relatively low, species may avoid
overlapping and maintain signals within the optimal frequency range of a
given habitat, but in species-rich communities, species will encounter greater
signal overlap and will be forced to use other frequencies. Our acoustic species
richness hypothesis unifies the acoustic partitioning and network hypotheses
by demonstrating how variation in species richness across sites affects the
patterns of activity within the acoustic space. This novel approach for
analysing soundscapes contributes to our understanding of ecological
community dynamics (e.g. niche theory) and provides useful tools for monitoring species in the context of restoration ecology, climate change, and
conservation biology. | |
