非线性鸣声对雄性凹耳蛙应答的影响

为了解非线性鸣声对凹耳蛙(Odorrana tormota)应答音的影响以及非线性鸣声是否能够增强鸣声的不可预测性,本研究通过回放非线性鸣声和线性鸣声来刺激陌生雄性凹耳蛙,并记录应答次数及统计分析应答音相关参数。结果表明,回放非线性鸣声时会引起陌生蛙(n=22)更多次数的应答,但两种刺激引起的首次应答时间没有显著差异。对应答音相关参数分析表明,线性鸣声引起的应答音在总时长上比非线性鸣声引起的应答音更长且具有显著差异,而其他声音参数(包括平均基频、最大基频、最小基频、主频)均没有显著差异。推测当陌生雄蛙听到同类鸣叫时,出于保护领地和资源的本能反应,陌生蛙都会第一时间作出反应,因此在两类声音的应答反应时间上并没有区别。而在应答次数上,非线性鸣声引起了凹耳蛙更多次数的应答,可能是由于鸣声中的非线性现象使得声音更加复杂,包含更多信息,容易提高声音接收者对这类声音的关注度。本研究结果表明,凹耳蛙鸣声中包含的非线性现象能够增强其声音的不可预测性,引起陌生蛙产生更多的应答次数。

The Influences of Nonlinear Phenomena on the Vocal Responses of Male Concave-eared Torrent Frogs (Odorrana tormota)

In order to explore the influences of nonlinear phenomena(NLP) on the vocal responses in concave-eared torrent frogs(Odorrana tormota), and whether NLP can enhance the unpredictability of calls, strange male concave-eared torrent frogs were stimulated by replaying NLP and linear calls(Fig. 1). The numbers of evoked vocal responses were recorded and the spectral and temporal parameters of response calls were analyzed. The results revealed that NLP calls could cause more response calls in strange frogs(n = 22, P < 0.05, Table 2), but there was no significant difference in the first response latency(P > 0.05, Table 3) of two kinds of evoked response calls. We then employed Praat to divide the calls into different temporal segments and obtain various temporal and spectral parameters. Wilcoxon’s signed rank test was used to determine whether there was significant difference in sound parameters of two kinds of evoked response calls. The results showed that the total duration of response calls stimulated by linear calls was longer than that of NLP-stimulated ones, while other vocal parameters, such as average fundamental frequency, maximum fundamental frequency, minimum fundamental frequency and dominant frequency, showed no significant difference(P > 0.05, Table 4). It was possible that strange male frogs would respond to the conspecific calls instantly in order to protect their territory and resources, however, there were no differences in response time to NLP calls and linear calls. In terms of response call numbers, more responses were stimulated by NLP calls which contain more complicated information, and thus increase the attention of the receiver. The current study reveals that the NLP calls will enhance vocal unpredictability and cause more responses of strange male frogs.