Female choice and male-male competition are affected by noise-filled calls in a treefrog

Both human and non-human animals communicating acoustically face the
problem of noise interference, especially anurans during mating
activities. Previous studies focused on the effect of continuous
noise on signal recognition, but it is still unknown
whether different notes in advertisement calls filled by
noise affect female choice and male-male competition or
not. In this study, we tested female preferences and male evoked
vocal responses in serrate-legged small
treefrog (Kurixalus odontotarsus), by broadcasting the five-note
advertisement call and the advertisement call with the second, third or
fourth note filled by noise respectively. In phonotaxis experiments,
females significantly discriminated against the
advertisement call with the fourth note filled by noise, although they did
not discriminate against other two noise-filled calls, which indicates
that the effect of noise on female preference is related to the order of
filled notes in the advertisement call. In playback experiments, males
increased the total number of notes and notes/call in response to
noise-filled calls compared with spontaneous calls.
More interesting, the vocal responses evoked by noise-filled
calls were similar to those evoked by complete advertisement calls,
suggesting that males may recognize the noise-filled calls as complete
advertisement calls. Taken together, our study shows that different notes
in advertisement calls filled by noise have different effects on female
choice and male-male competition.