Data from: The evolutionary origin of variation in song length and frequency in the avian family Cettiidae

Aspects of bird song have been shown to correlate with morphological and ecological features, including beak and body size, and habitat. Here we study evolution of song length and song frequency among 30 species belonging to the Cettiidae. Frequency is negatively correlated with body size, and song length increases with latitude. Although migration distance correlates with latitude, the association of song length with latitude is only present within the non-migratory species, implying the association is not a consequence of migration. We place these correlations in a historical framework to show that the body size-frequency association arose early in the group, but the latitude-song length association is more evolutionarily labile. We suggest that latitudinal correlates of song length may reflect increased importance of sexual selection by female choice.

已有研究表明，鸟类鸣唱的多项特征与形态学及生态学特征存在关联，其中包括喙部与体型大小，以及栖息环境。本研究针对隶属于树莺科（Cettiidae）的30个鸟类物种，探究其鸣唱时长与鸣唱频率的演化规律。研究发现，鸣唱频率与体型大小呈负相关，而鸣唱时长则随纬度升高而增加。尽管迁徙距离与纬度存在关联，但鸣唱时长与纬度的相关性仅存在于非迁徙性物种当中，这表明该相关性并非由迁徙行为所导致。我们借助演化历史框架对上述相关性展开溯源分析，结果显示体型与鸣唱频率的相关性在该类群演化早期便已确立，而鸣唱时长与纬度的相关性则更具演化不稳定性。我们据此提出，鸣唱时长的纬度相关性或许反映了雌性选择所介导的性选择作用愈发重要。