Data from: Incorporating color into integrative taxonomy: analysis of the varied tit (Sittiparus varius) complex in East Asia

Species designations are critically important scientific hypotheses that serve as the foundational units in a wide range of biological subdisciplines. A growing realization that some classes of data fail to delimit species under certain conditions has led to increasingly more integrative taxonomies, whereby species discovery and hypothesis testing are based on multiple kinds of data (e.g. morphological, molecular, behavioral, ecological, etc.). However, although most taxonomic descriptions have been based on morphology, some key morphological features, such as color, are rarely quantified and incorporated into integrative taxonomic studies. In this paper, we applied a new method of ultraviolet digital photography to measure plumage variation in a color-variable avian species complex, the varied tit (Sittiparus varius). Plumage measurements corroborated species limits defined by morphometric, mitochondrial DNA, and nuclear DNA disjunctions and provided the only evidence for recognizing two recently evolved species. Importantly, color quantification also provided a justification for lumping putative taxa with no evidence of evolutionary independence. Our revised taxonomy thus refines conservation units for listing and management and clarifies the primary units for evolutionary studies. Species tree analyses, which applied the newly delimited species as operational taxonomic units, revealed a robust phylogenetic hypothesis for the group that establishes a foundation for future biogeographic analyses. Our study demonstrates how digital photography can be used to incorporate color character variation into integrative taxonomies, which should lead to more informed, more rigorous, and more accurate assessments of biodiversity.物种界定（species designations）是至关重要的科学假说，亦是诸多生物学分支学科的核心基础单元。人们日益认识到，部分数据类型在特定条件下无法准确界定物种，这推动了整合分类学（integrative taxonomies）的发展——在该框架下，物种发现与假说验证基于多类数据（如形态学、分子生物学、行为学、生态学等）。然而，尽管多数分类学描述依托形态学数据开展，但诸如体色这类关键形态特征却极少被量化并纳入整合分类学研究范畴。本文采用紫外数码摄影（ultraviolet digital photography）新技术，对体色多变的鸟类物种复合体——杂色山雀（varied tit，*Sittiparus varius*）的羽色变异进行量化测量。羽色量化结果验证了由形态测量、线粒体DNA（mitochondrial DNA）及核DNA（nuclear DNA）分歧所界定的物种边界，同时为识别两个新近演化的物种提供了唯一依据。尤为重要的是，体色量化研究还为合并那些无演化独立性证据的推定分类单元提供了合理依据。我们修订后的分类系统优化了用于物种名录编制与保护管理的保护单元，并明确了演化研究的核心研究单元。本研究以新界定的物种作为操作分类单元（operational taxonomic units）开展物种树分析，最终得到该类群可靠的系统发育假说，为后续生物地理学研究奠定了坚实基础。本研究展示了如何利用数码摄影技术将体色特征变异纳入整合分类学研究，这将助力开展更具科学性、更严谨且更精准的生物多样性评估。