Individual variation in the advertisement call of Aplastodiscus albosignatus (Anura: Hylidae) is correlated with body size and environmental temperature

ABSTRACT

The importance of amphibian bioacoustics is widely documented in ecological, taxonomical and evolutionary studies, as calls might act as a primary mechanism of reproductive isolation. The influence of air temperature and male size on the variation of the advertisement calls in anurans is widely recognized but still insufficiently analyzed in Brazilian species. Our goals were to (1) describe the advertisement call of Aplastodiscus albosignatus (Lutz & Lutz, 1938), (2) test the influence of temperature and body size on its acoustic signals and (3) evaluate the variation of within and between-male acoustic signals. Advertisement calls of A. albosignatus consist of an unpulsed note with four harmonics. In most cases, the dominant frequency is the third harmonic but, in some calls, it was the minimum frequency (first harmonic). The average duration of calls was 0.191 s, the interval between calls was 2.08 s and the repetition rate was 33 calls per minute. On average, the minimum frequency was 550.15 Hz, the maximum frequency was 3531.70 Hz and the third harmonic was 2498.9 Hz. To evaluate the effect of air temperature, and body size on the variation of call parameters, we performed generalized linear models. The most explanatory model for spectral parameters was temperature plus body size. Concerning temporal variables, the best model that explains the variation in call duration was body size, while for the interval between calls was air temperature. The maximum frequency and the frequency of the third harmonic had little variation in the calls of both the same male and different males. Thus, these parameters were considered important in species recognition.(AU)