| The effective production of acoustic signals is critically important for intraspecific communication in vocal animals.Under natural conditions,however,communication in frogs will be affected by background noise,which may mask their acoustic signal and make the signal detection and recognition more difficulty,and affect the frogs'signal transmission,social communication and activities.Moreover,vocalization is also highly time-consuming,energetically demanding and likely to increase predation risks.Thus,we hypothesized that the biological significance of each component of complex acoustic signals would differ in their biological functions and that the first component of such signals would be most important for social signalling and would exhibits unique acoustic characteristics because of the precedence effect.To test this hypothesis,we measured temporal and spectral acoustic parameters for the first ten notes of the advertisement calls for each individual of the Anhui tree frog(Rhacophorus zhoukaiya),a species in which males build mud burrows and call from within these nests.Multivariate analyses including hierarchical cluster analysis,multidimensional scaling and discriminant analysis were used.The results showed that the first call notes formed one cluster while the others formed the other cluster in multidimensional space when the parameters measured were normalized.Furthermore,the temporal and spectral sound attributes of the first call note provide sufficient information for discrimination between different individuals.Moreover,discriminant analysis showed that the fundamental frequency of the first note was sufficient to identify individuals when the data were not normalized.Taken together,these results indicated that the first call note was poised to play an important role in Anhui tree frog vocal communication insofar as the temporal and spectral features provide sufficient information for individual recognition. |
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