ABSTRACT Acoustic signals used in animal communication play a key role in mate attraction, species recognition, and territory defense. Variation in acoustic signals may reflect population structure, lack of gene flow, and phylogenetic relationships. In birds, the study of geographic variation in acoustic signals has been useful for elucidating potential factors involved in phenotypic divergence and for establishing species limits. However, most of the studies on geographic variation have focused on calls and solo songs, with few studies focusing on complex behaviors such as duets. In this study, we investigated the variation in the duets of the Rufous-naped Wren (Campylorhynchus rufinucha). Our results suggest that duets vary across the distribution range of the species complex, matching the 3 taxonomic groups previously suggested (rufinucha, humilis, and capistratus). We also found a marked song sexual dimorphism in 2 groups, rufinucha and humilis, that is lacking in capistratus. At the local level, we found that duets also vary among sites within groups, but less than between groups. Our results suggest that groups rufinucha and humilis sing the most similar duets, whereas capistratus performs the most divergent duets of the 3 groups. Further, when comparing duet variation across geography, we found that birds living closer to each other sing more similar duets. We suggest that the existence of 3 vocal lineages is probably the result of historical geographic isolation followed by other selective (i.e. sexual selection, social selection, habitat structure) and/or non-selective factors (i.e. drift, isolation by distance), and that variation found within groups may be the result of cultural drift or social selection.

中文翻译：

---

棕枕鹪鹩（Campylorhynchus rufinucha）复合体二重唱的地理变异

摘要 动物交流中使用的声学信号在吸引配偶、物种识别和领土防御方面起着关键作用。声学信号的变化可能反映了种群结构、基因流的缺乏和系统发育关系。在鸟类中，声学信号的地理变异研究有助于阐明与表型差异相关的潜在因素和确定物种限制。然而，大多数关于地理变异的研究都集中在通话和独奏歌曲上，很少有研究关注二重奏等复杂行为。在这项研究中，我们调查了棕枕鹪鹩（Campylorhynchus rufinucha）二重唱的变化。我们的结果表明，二重奏在物种复合体的分布范围内有所不同，与之前建议的 3 个分类群（rufinucha、humilis 和 capistratus）。我们还在 rufinucha 和 humilis 2 组中发现了明显的歌曲性别二态性，这是 capistratus 所缺乏的。在地方层面，我们发现二重唱在组内站点之间也有所不同，但小于组之间。我们的结果表明 rufinucha 和 humilis 组唱的二重唱最相似，而 capistratus 执行三组中最不同的二重唱。此外，在比较不同地区的二重唱变化时，我们发现生活得更近的鸟类唱的二重唱更相似。我们认为 3 个声系谱系的存在可能是历史地理隔离的结果，其次是其他选择性（即性选择、社会选择、栖息地结构）和/或非选择性因素（即漂移、距离隔离），