山地隔离和空间距离对高黎贡山灰腹地莺(Tesia cyaniventer)鸣唱特征的影响

鸟类鸣唱存在广泛的地理变异，研究鸟类鸣唱变异的模式及其影响因素可帮助解释自然界中广泛而复杂的鸣声变异现象。灰腹地莺（Tesia cyaniventer）是在高黎贡山海拔2000-2800 m分布的小型地栖性森林鸟类。高黎贡山南北走向的山脊海拔通常在3000m以上，这导致灰腹地莺东、西坡种群被山脊所隔离。该种小鸟鸣声洪亮易于鉴别，其鸣声地理变异可揭示山地对鸟类种群产生的隔离效应。在高黎贡山片马垭口和独龙江垭口的东西坡4个地点录制了灰腹地莺的鸣声（n=58），基于声谱分析比较了种群间鸣唱的质量特征，发现种群间鸣唱型的共享程度极低，而音节型在4个种群间均有共享。进一步测量了11个鸣唱的数量特征参数，有6个参数在不同种群间有显著差异：最低频率、中心频率、频率宽度、起始音节频率、首二音节的时间间隔、句子平均音节数。种群间的两两比较表明，鸣声特征差异呈现"隔离-距离"共同作用的格局，但隔离的影响更大。研究表明山地系统中影响鸟类鸣声地理变异的因素较为复杂，山地隔离和空间距离均对灰腹地莺的鸣唱特征产生了影响。

Effects of mountain barrier and spatial distance on acoustic characteristics of a ground-dwelling forest bird (Tesia cyaniventer) in the Gaoligong Mountains

Bird vocalization plays an important role in the ecology and evolution of birds, particularly in passerine birds (songbirds). Like other phenotypes, the vocalization of passerines has shown extensive geographical variations between populations that are isolated by geographical barrier and spatial distance. The relative role of geographical barrier and spatial distance in affecting the variation of vocal variation between populations within species is rarely tested. The Tesia cyaniventer is a small ground-dwelling forest species that distributes between 2000-2800 m in elevation at the Gaoligong Mountains, which is a chain of mountains run from north to south in southwestern China. The western and eastern populations of the Tesia cyaniventer are isolated by mountain peaks above 3000 m, making it an ideal model species to test the relative attributions of geographical barrier and spatial distance to vocal variations between populations. In the breeding season in 2016 and 2018, we recorded and measured 1268 songs of 58 individuals from four populations in the north and south sections of the Gaoligong Mountains, with two sampling sites in each section on east slope and west slope, respectively. We identified 38 song types and 58 syllable types from four populations. Different populations shared few song types in common, while the syllable types shared to a certain extent among the four populations. We measured 11 acoustic traits of each song and compared these traits among four populations. Six of the 11 acoustic traits being measured differed significantly among populations, including lowest frequency (P <0.001), the center frequency (P=0.031), the delta frequency (P=0.008), the introductory syllable frequency (P=0.04), the time interval between the first and second syllables (P=0.001), and the average number of each song (P=0.005). Inter-population comparisons showed that the geographical barrier might have a stronger effect than the spatial distances, although both of them might attribute to variations of song characteristics. Specifically, three acoustic traits showed significant difference between populations with long distance and that are isolated by mountain peak; two acoustic traits showed significant difference between populations only isolated by mountain peak; and only one trait was significant different between populations only affected by geographical distance. Overall, our results showed that the factors affecting the variations might be rather complex, as the mountain barrier and the geographical distance have different isolation effects on acoustic traits of the populations of the Tesia cyaniventer.