The first two functionally antagonistic call notes influence female choice in the Anhui tree frog

Description

The present study used phonotaxis experiments to examine the effects of the notes on female choice in the Anhui tree frog (Rhacophorus zhoukaiyae). The stimulus pair consisted of the original male advertisement call (OC) and one of four revised versions, where the first (WN1), second (WN2), or fifth (WN5) notes were replaced by band-limited white noise (WN), and the second note was replaced by a period of silence (SN2), played back antiphonally. The results showed that (1) the females preferred OC compared with WN1, suggesting the first call note plays an important role in female choice, and (2) the females preferred WN2 and SN2 compared with OC. We discuss the possibility that the second note might be the result of the combined effects of physiological constraint and avoiding backward masking of the second note on the first one over evolutionary time. These results support the notion that the first two functionally antagonistic call notes may influence female choice in this species. The data is provided in Excel (.xlsx) format.

Steps to reproduce

Study site: We captured 84 gravid female Anhui tree frogs in Jinzhai County, within the Dabie Mountain area of Anhui Province, China (31.28° N, 115.72° E; elevation: 870 m above sea level). Stimulus preparation: Five types of stimuli were employed in this study: the original advertisement call (OC); and four modified versions of the OC: WN1 (the first note replaced by band-limited white noise), WN2 (the second note replaced by band-limited white noise), WN5 (the fifth note replaced by band-limited white), and SN2 (the second note replaced by a period of silence). Experimental Setup: An open wooden tank (270 cm × 95 cm × 100 cm) was set up outdoors. Two speakers were positioned at opposite tank ends, equidistant from each other, with the output intensity calibrated to 80 dB SPL. Two infrared cameras were installed above the tank to monitor the behaviour of each subject. Phonotaxis Experiment: Experiments were conducted at night (20:00-03:00). For each test, a subject was placed under a transparent semicircular plastic cup and allowed to habituate for approximately 3 min in darkness. Then, one of the stimulus pairs (e.g., OC vs. WN1, OC vs. WN2, OC vs. WN5, OC vs. SN2) was selected and played back antiphonally with a 3.5 s inter-stimulus interval. Subjects' choices were recorded based on whether or not they approached within 10 cm of the speaker during the 20 min period. If the subject did not make a choice within 20 min, it was recorded as "no preference". The above steps were repeated for each subject and for each pair of stimuli. Data collection and analysis: For each subject, the number of choices and the latencies of choice were analyzed. Then data were further analyzed using appropriate statistical tests (e.g., chi-square test, binomial test, t-test).

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