Animal signals in multiple modalities expands the opportunity for effective communication. Among diurnal geckos of the genus Cnemaspis, chemical signalling traits preceded the evolution of visual traits. Males of all species possess chemical secreting ventral glands, but only in some species, males also express yellow gular patches. This difference in the expression of unimodal or multimodal signalling traits between closely related species provided us with an opportunity to understand the use of multimodal signals for communication. We studied receiver responses in Cnemaspis indica, a sexually monochromatic species, and in C. littoralis, a species where males possess yellow gulars. We performed behavioural trials where individuals of each species were exposed to only chemical stimuli, only visual stimuli, or both chemical and visual stimuli simultaneously from male and female conspecifics. Our results show that only chemical stimuli were necessary and sufficient to elicit responses in males and females of C. indica as well as in females of C. littoralis. However, males of the dimorphic C. littoralis required the multimodal stimulus to elicit movement-based responses. Our results suggest that the evolution of colour traits in diurnal geckos is associated with a partial shift in some receiver responses toward multimodal communication, with no addition to the behavioural repertoire.

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添加新的信号特征是否会增强昼行壁虎的接收器响应？

多种形式的动物信号扩大了有效沟通的机会。在 Cnemaspis 属的昼行壁虎中，化学信号特征先于视觉特征的进化。所有物种的雄性都有分泌化学物质的腹腺，但只有在某些物种中，雄性也会表达黄色的唇斑。密切相关物种之间单峰或多峰信号特征表达的这种差异为我们提供了了解多峰信号用于交流的机会。我们研究了 Cnemaspis indica（一种性单色物种）和 C. littoralis（一种雄性具有黄色 gulars 的物种）中的接收者反应。我们进行了行为试验，其中每个物种的个体仅暴露于化学刺激、仅视觉刺激、或同时来自男性和女性同种动物的化学和视觉刺激。我们的结果表明，只有化学刺激是必要和足够的，才能在 C. indica 的雄性和雌性以及 C. littoralis 的雌性中引起反应。然而，双态 C. littoralis 的雄性需要多模式刺激来引发基于运动的反应。我们的结果表明，昼行壁虎颜色特征的演变与某些接收器响应向多模式通信的部分转变有关，而没有增加行为清单。littoralis 需要多模式刺激来引发基于运动的反应。我们的结果表明，昼行壁虎颜色特征的演变与某些接收器响应向多模式通信的部分转变有关，而没有增加行为清单。littoralis 需要多模式刺激来引发基于运动的反应。我们的结果表明，昼行壁虎颜色特征的演变与某些接收器响应向多模式通信的部分转变有关，而没有增加行为清单。