No phenotypic signature of acoustic competition in songs of a tropical cricket assemblage

Efficient acoustic communication in multispecies assemblages is challenging due to the presence of heterospecific signals. Masking
interference and signal confusion of similarly structured signals can impose fitness costs and, thus, drive evolutionary processes that
shape acoustic signals to reduce their overlap in signal space. Although the partitioning of signal space has been frequently studied
in frog and bird communities, this topic has received much less attention with reference to insects that communicate acoustically. In
this study, we examined the role of acoustic competition in a tropical cricket community and tested the following hypotheses: 1) cosig-
naling  species  are  expected  to  exhibit  more  dissimilar  calling  songs  as  compared  with  species  that  are  spatially  and/or  temporally 
separated  and  2)  species  signaling  with  similar  song  frequencies,  who  are  thereby  subject  to  energetic  masking,  are  more  likely  to 
differ  in  the  temporal  domain  of  their  calling  songs.  Using  non-metric  multidimensional  scaling  and  pairwise  comparison  methods  to 
measure  acoustic  dissimilarity,  we  found  no  evidence  for  either  hypothesis:  the  acoustic  signals  of  species  pairs  that  cosignaled  or 
used similar calling frequencies did not significantly differ from those of species that were spatially/temporally segregated or had large
song frequency differences. In conclusion, for the acoustically communicating cricket community investigated, no supportive evidence
for the partitioning hypothesis and the widespread belief that acoustic competition has led to divergent selection pressures on signal
structure to avoid masking interference was found. Instead, we argue that selection pressures on sensory/neuronal mechanisms seem
to more strongly drive reliable communication.