Evoked Vocal Responses Change with Experience in Male Physalaemus pustulosus
The acquisition of signals used in intrasexual communication is not well studied. To better understand the possible contribution of early experience to the acquisition of intrasexual responses, we reared Neotropical Túngara frogs, Physalaemus pustulosus, in four acoustic environments: 1) conspecific chorus, 2) heterospecific chorus, 3) acoustic isolation, and 4) noise. For the heterospecific chorus, we chose the calls of a congener, P. enesefae, with which P. pustulosus is sympatric in parts of its distribution. We measured the evoked vocal responses (EVR) of these frogs in response to calls of the conspecifics, to calls of the congener, and to calls representing an intermediate between the two species. Male P. pustulosus reared hearing the calls of P. enesefae produced more calls overall and more complex calls in response to the call of P. enesefae. This is consistent with the hypothesis that the EVR of male anurans can be influenced by early experience and is the product of an interaction between genes and the environment.
Stimuli used for the tests of male-evoked vocal response: (A) simple P. pustulosus call; (B) complex P. pustulosus call with one chuck; (C) call of the congener P. enesefae; (D) intermediate call with acoustic characteristics between P. pustulosus and P. enesefae (see text); and (E) amplitude-modulated noise.
Change in call production when the control stimulus “noise” is paired with the experimental stimulus “intermediate” call for all four early acoustic experience groups: P. pustulosus-reared, P. enesefae-reared, isolation-reared, and noise-reared. A positive number indicates an increase in calling to the intermediate call. P. enesefae-reared males increased calling more than males reared in other conditions, and this difference is significant when the P. enesefae-reared group is compared to the group reared hearing noise. Bars represent 95% confidence intervals.
Change in production of chucks when the control stimulus “noise” is paired with the experimental stimulus “intermediate” call for all four early acoustic experience groups: P. pustulosus-reared, P. enesefae-reared, isolation-reared, and noise-reared. P. enesefae-reared males produced more chucks than frogs reared in other conditions, and this difference is significant when the P. enesefae-reared group is compared to all other groups. Bars represent 95% confidence intervals.
Change in production of calls when the control stimulus “noise” is paired with the P. enesefae experimental stimulus, for all four early acoustic experience groups: P. pustulosus-reared, P. enesefae-reared, isolation-reared, and noise-reared. P. enesefae-reared males produced more calls than frogs reared in other conditions, and this difference is significant when the P. enesefae-reared group is compared to the P. pustulosus-reared and noise-reared groups. Bars represent 95% confidence intervals.
Change in production of chucks when the control stimulus “noise” is paired with the P. enesefae experimental stimulus, for all four early acoustic experience groups: P. pustulosus-reared, P. enesefae-reared, isolation-reared, and noise-reared. P. enesefae-reared males produced more chucks than did frogs reared in other conditions, and this difference is significant when the P. enesefae-reared group is compared to the P. pustulosus-reared and noise-reared groups. Bars represent 95% confidence intervals.
Contributor Notes
Associate Editor: J. F. Schaefer.