Vocal communication plays an important role in survival, reproduction, and animal social association. Birds and mammals produce complex vocal sequence to convey context-dependent information. Vocalizations are conspicuous features of the behavior of most anuran species (frogs and toads), and males usually alter their calling strategies according to ecological context to improve the attractiveness/competitiveness. However, very few studies have focused on the variation of vocal sequence in anurans. In the present study, we used both conventional method and network analysis to investigate the context-dependent vocal repertoire, vocal sequence, and call network structure in serrate-legged small treefrogs Kurixalus odontotarsus. We found that male K. odontotarsus modified their vocal sequence by switching to different call types and increasing repertoire size in the presence of a competitive rival. Specifically, compared with before and after the playback of advertisement calls, males emitted fewer advertisement calls, but more aggressive calls, encounter calls and compound calls during the playback period. Network analysis revealed that the mean degree, mean closeness, and mean betweenness of the call networks significantly decreased during the playback period, which resulted in lower connectivity. In addition, the increased proportion of one-way motifs and average path length also indicates that the connectivity of the call network decreased in competitive context. However, the vocal sequence of K. odontotarsus did not display a clear small-world network structure, regardless of contexts. Our study presents a paradigm to apply network analysis to vocal sequence in anurans and has important implications for understanding the evolution and function of sequence patterns.

中文翻译：

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网络分析揭示了锯齿腿小树蛙社会呼唤的上下文相关结构复杂性

声音交流在生存、繁殖和动物社会交往中起着重要作用。鸟类和哺乳动物产生复杂的声音序列来传达上下文相关的信息。发声是大多数 anuran 物种（青蛙和蟾蜍）行为的显着特征，雄性通常根据生态环境改变它们的呼叫策略以提高吸引力/竞争力。然而，很少有研究关注无尾目动物发声顺序的变化。在本研究中，我们使用常规方法和网络分析来研究锯齿腿小树蛙 Kurixalus odontotarsus 的上下文相关发声曲目、发声序列和呼叫网络结构。我们发现男性 K. odontotarsus 通过切换到不同的呼叫类型和在存在竞争对手的情况下增加曲目大小来修改他们的声音序列。具体来说，与广告叫声播放前后相比，男性在播放期间发出的广告叫声较少，但攻击性叫声、遭遇叫声和复合叫声较多。网络分析显示，呼叫网络的平均度数、平均紧密度和平均介数在播放期间显着降低，从而导致连接性降低。此外，单向模体比例和平均路径长度的增加也表明呼叫网络的连通性在竞争环境中下降。然而，无论上下文如何，K. odontotarsus 的声音序列都没有显示出清晰的小世界网络结构。