Integrative revision of species limits in the genus Schiffornis (Aves: Tityridae) reveals cryptic diversity in the Neotropics

Accurate species delimitation is essential for many biological subdisciplines.Nonetheless, taxonomic research has shown that current species diversity is underestimated,even in some of the best-studied groups of animals. Recent acoustic and genetic studies haveuncovered many morphologically cryptic bird species that were previously hidden bymorphology-based classifications. Yet, current estimates of bird species-level diversity in thetropics remain rooted in early morphological classifications, and so the need for integrativetaxonomic revision is urgent. Here, we take an integrative approach to examine species limitsin the genus Schiffornis, a widespread group of dull-plumaged, whistle-voiced suboscinepasserines of Neotropical humid-forest understory, currently considered to comprise sevenspecies. We measured geographic variation in song, morphology, and mitochondrial andgenome-wide nuclear markers to resolve the taxonomy of the genus. Our results suggest thatSchiffornis comprises 13 separately evolving population lineages, of which most qualify asspecies taxa under all species definitions. These include a cryptic new species, several speciessplits, and the resurrection of a taxon that was synonymized nearly a century ago in the S.turdina complex. We also found several hitherto unnoticed contact zones between diverginglineages and a leapfrog pattern of song variation in the S. turdina complex, and we highlightpotential avenues of further research of this genus精准的物种界定对于诸多生物学子学科而言至关重要。然而，分类学研究表明，当前的物种多样性被低估，即便在一些研究最为充分的动物类群中亦是如此。近期的声学与遗传学研究已揭示了诸多在基于形态学的分类体系中被掩盖的形态隐秘鸟类类群。不过，当前对热带地区鸟类物种层级多样性的估算仍依托于早期的形态分类框架，因此开展整合分类学修订的需求极为迫切。本研究采用整合分类学方法，对希夫霸鹟属（Schiffornis）的物种界限展开探究。该属是广泛分布于新热带区湿润林下层的羽色暗淡、鸣啭为哨音的亚鸣禽类群，目前被认为包含7个物种。我们通过测量鸣声、形态特征以及线粒体和全基因组核标记的地理变异，以厘清该属的分类学问题。研究结果显示，希夫霸鹟属包含13个独立演化的种群支系，其中绝大多数符合所有物种定义下的物种类群标准。这些类群涵盖1个隐存新物种、多个物种拆分案例，以及恢复了一个近一个世纪前在S. turdina复合群中被归入同物异名的类群的分类地位。我们还在分化支系间发现了此前未被记录的接触带，同时在S. turdina复合群中观测到鸣声变异的跳跃式分布模式，并指出了该属未来可开展的若干研究方向。