Bidirectional communication system in katydids: The effect on chorus structure

Unlike most acoustic systems evolved for pair formation where only males signal, the katydid Phaneroptera nana has a bidirectional communication system where both males and females sing. Despite extensive study on male chorusing behavior in different communication systems, this behavior has rarely been explored in duetting species. I examined how this bidirectional communication system affects the collective pattern of male signaling. P. nana males alternate their songs, and in response to synthetic stimuli delay their calls, according to the phase of stimulation. Pairs of synthetic calls (simulating alternating males) presented to females elicited equal female response, as long as the intercall interval was ≤ 200 ms. Thus, male alternation is imposed by the female's responsiveness and may be interpreted as a "jamming avoidance reaction". Further evidence suggests that chorus structure is not merely constrained by the female sensory temporal resolution, but rather is adaptively related to female choice in this species.