Despite the acknowledged importance of defining avian species limits to scientific research, conservation, and management, in practice, they often remain contentious. This is true even among practitioners of a single species concept and is inevitable owing to the continuous nature of the speciation process, our incomplete and changing understanding of individual cases, and differing interpretations of available data. This issue of Ornithology brings together several papers on species limits, some more theoretical and general, and others case studies of specific taxa. These are viewed primarily through the lens of the biological species concept (BSC), by far the most widely adopted species concept in influential ornithological works. The more conceptual contributions focus on the importance of the integrative approach in species delimitation; the importance of considering selection with the increasing use of genomic data; examinations of the effectiveness of the Tobias et al. character-scoring species limits criteria; a review of thorny issues in species delimitation using examples from Australo-Papuan birds; and a review of the process of speciation that addresses how population divergence poses challenges. Case studies include population genomics of the American Kestrel (Falco sparverius); an integrative taxonomic analysis of Graceful Prinia (Prinia gracilis) that suggests two species are involved; and a reevaluation of species limits in Caribbean Sharp-shinned Hawk (Accipiter striatus) taxa.

中文翻译：

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鸟类的物种限制和分类

尽管定义鸟类物种限制对科学研究、保护和管理的重要性已得到公认，但在实践中，它们往往仍然存在争议。即使在单一物种概念的从业者中也是如此，并且由于物种形成过程的连续性、我们对个别案例的不完整和不断变化的理解以及对可用数据的不同解释，这是不可避免的。本期鸟类学汇集了几篇关于物种限制的论文，一些更具理论性和一般性，以及其他特定分类群的案例研究。这些主要是通过生物物种概念（BSC）的镜头来看待的，这是迄今为止在有影响力的鸟类学著作中采用最广泛的物种概念。更多的概念性贡献集中在物种划界中综合方法的重要性；随着基因组数据使用的增加，考虑选择的重要性；Tobias 等人的有效性检查。特征评分物种限制标准；以澳大利亚-巴布亚鸟类为例，回顾物种划界中的棘手问题；以及对物种形成过程的回顾，以解决种群差异如何带来挑战。案例研究包括美洲红隼（Falco sparverius）的种群基因组学；Graceful Prinia (Prinia gracilis) 的综合分类学分析表明涉及两个物种；以及重新评估加勒比尖尾鹰（Accipiter striatus）分类群的物种限制。以澳大利亚-巴布亚鸟类为例，回顾物种划界中的棘手问题；以及对物种形成过程的回顾，以解决种群差异如何带来挑战。案例研究包括美洲红隼（Falco sparverius）的种群基因组学；Graceful Prinia (Prinia gracilis) 的综合分类学分析表明涉及两个物种；以及重新评估加勒比尖尾鹰（Accipiter striatus）分类群的物种限制。以澳大利亚-巴布亚鸟类为例，回顾物种划界中的棘手问题；以及对物种形成过程的回顾，以解决种群差异如何带来挑战。案例研究包括美洲红隼（Falco sparverius）的种群基因组学；Graceful Prinia (Prinia gracilis) 的综合分类学分析表明涉及两个物种；以及重新评估加勒比尖尾鹰（Accipiter striatus）分类群的物种限制。