Behaviour 2019
Why do male Pacific chorus frogs produce two advertisement calls? Insights from female behavior
Esther Clemence Batarse, Alejandro Velez. San Francisco State University, San Francisco, CA, United States

Communication signals mediate biologically important behaviors like species recognition and sexual selection. The advertisement call is the most common signal produced by male frogs during the breeding season and is used to attract females and repel other males. Interestingly, male Pacific chorus frogs, Hyliola regilla, produce two types of advertisement calls. These calls, aptly known as monophasic and diphasic, are used interchangeably during the night. Why males produce two different calls is still unclear. We asked: 1. Do both types of calls attract females? And 2. Do females prefer one call over the other? In no-choice playback experiments, when only one type of call was broadcast at a time, females showed similar positive responses to both calls. Overall, females did not prefer one type of call over the other when given a choice between them in two-choice playback experiments. For some males, however, their monophasic calls were more attractive than their diphasic calls. We discuss potential sensory mechanisms underlying our results and how mechanisms akin to frequency-dependent selection or conditional mating strategies may explain the maintenance of two advertisement calls.