Data from: Genetic, morphological and acoustic evidence reveals lack of diversification in the colonization process in an island bird

Songbirds with recently (i.e. early Holocene) founded populations are suitable models for studying incipient differentiation in oceanic islands. On such systems each colonization event represents a different evolutionary episode that can be studied by addressing sets of diverging phenotypic and genetic traits. We investigate the process of early differentiation in the spectacled warbler (Sylvia conspicillata) in 14 populations separated by sea barriers from three Atlantic archipelagos and from continental regions spanning from tropical to temperate latitudes. Our approach involved the study of sexual acoustic signals, morphology and genetic data. Mitochondrial DNA did not provide clear population structure. However, microsatellites analyses consistently identified two genetic groups, albeit without correspondence to subspecies classification and little correspondence to geography. Coalescent analyses showed significant evidence for gene flow between the two genetic groups. Discriminant analyses could not correctly assign morphological or acoustic traits to source populations. Therefore, although theory predicting that in isolated populations genetic, morphological or acoustic traits can lead to radiation, we have strikingly failed to document differentiation on these attributes in a resident passerine throughout three oceanic archipelagos.

新近（即全新世早期）形成种群的鸣禽，是研究大洋岛屿内物种初期分化的理想模型类群。在此类系统中，每一次殖民事件均代表一个独立的演化进程，可通过分析一系列趋异的表型与遗传性状开展相关研究。本研究以眼镜森莺（Sylvia conspicillata）为对象，探究其早期分化过程：该物种的14个种群被海洋屏障分隔，分布于3个大西洋群岛以及横跨热带至温带纬度的大陆区域。本研究的分析手段涵盖性声学信号、形态学与遗传学数据。其中，线粒体DNA (mitochondrial DNA) 未检测到清晰的种群遗传结构；不过，微卫星标记 (microsatellites) 分析始终识别出两个遗传类群，尽管该结果与亚种分类几乎无对应关系，且与地理分布的关联度极低。溯祖分析 (coalescent analyses) 结果显示，这两个遗传类群间存在显著的基因交流证据。判别分析 (discriminant analyses) 无法将形态或声学性状准确归类至其源种群。因此，尽管现有理论预测，孤立种群的遗传、形态或声学性状可推动物种辐射演化，但本研究却意外发现，这3个大洋群岛中的居留性雀形目鸟类 (passerine) 并未在上述三类性状上呈现出显著分化。