Data from: Divergence in mating signals correlates with genetic distance and behavioural responses to playback

Animals use acoustic signals to defend resources against rivals and attract breeding partners. As with many biological traits, acoustic signals may reflect ancestry; closely related species often produce more similar signals than do distantly related species. Whether this similarity in acoustic signals is biologically relevant to animals is poorly understood. We conducted a playback experiment to measure the physical and vocal responses of male songbirds to the songs of both conspecific and allopatric-congeneric animals that varied in their acoustic and genetic similarity. Our subjects were territorial males of four species of neotropical Troglodytes wrens: Brown-throated Wrens (Troglodytes brunneicollis), Cozumel Wrens (T. beani), Clarion Wrens (T. tanneri), and Socorro Wrens (T. sissonii). Our results indicate that birds respond to playback of both conspecific and allopatric-congeneric animals; that acoustic differences increase with genetic distance; and that genetic divergence predicts the strength of behavioural responses to playback, after removing the effects of acoustic similarity between subjects’ songs and playback stimuli. Collectively, these results demonstrate that the most distantly related species have the most divergent songs, that male wrens perceive divergence in fine structural characteristics of songs, and that perceptual differences between species reflect evolutionary history. This study offers novel insight into the importance of acoustic divergence of learned signals and receiver responses in species recognition.

动物通过声学信号（acoustic signals）抵御竞争者以捍卫资源，并吸引繁殖配偶。如同诸多生物学性状，声学信号可反映物种的祖先起源；亲缘关系较近的物种所产生的信号，通常比远缘物种更为相似。目前学界对这类声学信号相似性是否与动物存在生物学关联仍知之甚少。本研究开展了回放实验（playback experiment），以测定雄性鸣禽对同种（conspecific）以及异地同属（allopatric-congeneric）动物鸣唱的物理与声学反应，这些受试鸣唱的声学与遗传相似性各有差异。本研究的受试对象为4种新热带区鹪鹩属（Troglodytes）的领域性雄性个体：棕喉鹪鹩（Troglodytes brunneicollis）、科苏梅尔鹪鹩（T. beani）、克拉里昂鹪鹩（T. tanneri）以及索科罗鹪鹩（T. sissonii）。研究结果显示：鸣禽会对同种以及异地同属物种的回放鸣唱产生反应；声学差异随遗传距离（genetic distance）增大而增加；在排除受试个体鸣唱与回放刺激之间的声学相似性影响后，遗传分化（genetic divergence）可预测动物对回放实验的行为反应强度。综合来看，这些结果表明：亲缘关系最远的物种，其鸣唱差异也最大；雄性鹪鹩能够感知鸣唱精细结构特征的差异；且物种间的感知差异反映了物种的演化历史。本研究为揭示习得性信号的声学分化以及接收者反应在物种识别（species recognition）中的重要性提供了全新视角。