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宏条形码可以快速检测群落中的生物多样性组成，因此被广泛应用于生物多样性监测和群落生态学研究。分类操作单元(OTU)聚类阈值的选择是宏条形码分析中的关键环节，但目前尚缺乏对阈值适用性的全面评估。本研究系统综述了2015—2024年间以昆虫宏条形码为主题的338项研究，并对其OTU聚类阈值、标记基因及涉及类群等进行了统计分析。结果显示，近70%的昆虫宏条形码研究采用97%的种级相似性阈值，且该阈值并未随标记基因或分类阶元的变化而调整。当前很多宏条形码研究中OTU聚类阈值的选择普遍存在习惯化倾向，97%相似性阈值被作为默认标准在不同生物类群中广泛沿用，但该阈值源于细菌分类早期研究，并非基于对昆虫和其他真核生物类群的全面调研。鉴于不同昆虫类群及标记基因的演化速率存在差异，简单应用单一阈值容易导致物种多样性评估的偏差，从而为后续分析引入系统性偏差。为提高基于宏条形码在生物多样性监测应用中的可靠性，建议结合目标类群及基因标记特性，建立更具客观性和针对性的物种界定标准。
Abstract：Metabarcoding enables rapid assessment of biodiversity and composition of communities and is therefore widely used in biodiversity monitoring and community-level ecological research. The selection of operational taxonomic unit(OTU) clustering thresholds is a critical step in metabarcoding analyses. However, the threshold applicability remains to be comprehensively evaluated. In this study, by systematically reviewing 338 insect metabarcoding studies published between 2015 and 2024, we analyzed the OTU clustering thresholds, genetic markers, and involved taxonomic groups. Our results showed that nearly 70% of the studies adopted a 97% sequence similarity threshold at the species level, which was rarely adjusted in response to different marker genes or taxonomic groups. It seemed that the selection of OTU clustering thresholds in many metabarcoding studies was often based on common practice, with the 97% similarity threshold being widely adopted as a default standard in various biological groups. In fact, this threshold originated from early studies on bacterial classification and was not based on comprehensive evaluation for insects and other eukaryotic groups. Given the variations in evolutionary rate among different insect groups and marker genes, simple application of a single threshold may cause over-splitting or under-merging of OTUs, thereby introducing systematic bias in subsequent analyses. To improve the reliability of biodiversity monitoring based on metabarcoding, we recommend establishing more objective and targeted species delimitation criteria by integrating the characteristics of target taxa and genetic markers.
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基本信息:
DOI：10.15914/j.cnki.wykx.2026006
中图分类号:Q969
引用信息:
[1]辛佳朔,彭欣,张健,等.昆虫宏条形码研究中OTU聚类阈值使用的现状和问题[J].武夷科学,2026,42(01):1-10.DOI:10.15914/j.cnki.wykx.2026006.
基金信息:
国家自然科学基金(32270499); 国家科技基础资源调查专项(2022FY100500)
2026-03-30
2026-03-30
2026-03-30