So similar and yet so different: taxonomic status of Pallid Swift <i>Apus pallidus</i> and Common Swift <i>Apus apus</i>

<b>Capsule:</b> Common Swift <i>Apus apus</i> and Pallid Swift <i>Apus Pallidus</i> are morphologically very similar but are genetically distinct and diverged 1.9–2.1 million years ago (mya). <b>Aims:</b> To examine genetic differentiation and to estimate separation time between Common and Pallid Swifts. <b>Methods:</b> Estimation of differences in three different mitochondrial DNA markers (<i>COI</i>, <i>ND2</i> and control region), and a fourth marker, the <i>cytb</i>, that did not differ between taxa. Fossils were used to calibrate the estimate of separation date between the two taxa. <b>Results:</b> The genetic between-species distances were 0.010, 0.006 and 0.033 for the three markers, respectively. These values were from three to ten times higher than within-species distances. Results show that the separation dates back to 1.9–2.1 mya, at the Plio-Pleistocene transition, when global climate underwent a period of significant cooling and Northern latitudes were probably more favourable to the Common than to the Pallid Swift. <b>Conclusion:</b> Differences in breeding biology, migration, moult and vocalizations between the two species are mirrored by a clear genetic separation.

**概要：** 普通雨燕（Common Swift, *Apus apus*）与苍白雨燕（Pallid Swift, *Apus pallidus*）在形态学上高度相似，但遗传特征存在显著分化，二者的分化时间为190万至210万年前（mya，million years ago）。
**研究目的：** 探究普通雨燕与苍白雨燕之间的遗传分化情况，并估算二者的分化时间。
**研究方法：** 选取三种不同的线粒体DNA（mitochondrial DNA）标记——COI、ND2以及线粒体控制区，同时引入第四种标记细胞色素b（cytb），但该标记在两类群间未检测到序列差异；通过化石数据对两类群的分化时间估算进行校准。
**研究结果：** 上述三种标记的种间遗传距离分别为0.010、0.006和0.033，该数值较种内遗传距离高出3至10倍。结果显示，两类群的分化时间可追溯至190万至210万年前，即上新世-更新世过渡（Plio-Pleistocene transition）时期，彼时全球气候经历了显著降温阶段，北半球的生境或许更适宜普通雨燕生存，而非苍白雨燕。
**研究结论：** 两种类群在繁殖生物学、迁徙行为、换羽习性以及鸣唱特征上的差异，与其清晰的遗传分化特征形成了良好的呼应。

搜集汇总

背景与挑战

背景概述

该数据集通过分析线粒体DNA标记和化石校准，研究了Pallid Swift和Common Swift的遗传分化，估计它们在大约190-210万年前的Plio-Pleistocene过渡期分离，并揭示了形态相似性与遗传差异之间的对比。研究结果支持了两种鸟类在分类学上的独立地位，并关联到历史气候变化的影响。