| 摘要: |
| 运用高通量测序技术分析微型生物多样性时, 生物学重复间常表现出明显的异质性, 这可能是高比例的稀有可操作分类单元(operated taxonomic unit, OTU)造成的“假象”。为明晰陆架海区站位间及同一站位重复间底栖纤毛虫群落的异质性水平, 并探明稀有OTU与群落异质性的关系, 给出去除稀有OTU阈值的科学建议。本研究在东海选取具有明显环境梯度的4个站位, 每站位采集3个重复沉积物, 采用高通量测序技术研究纤毛虫群落与分布。研究表明同一站位重复间群落不相似度在30%~34%, 重复间群落的高差异性会掩盖地理距离较近的站位间差异(33%)。各个站位重复间共有OTU分别占该站位检获的总OTU数的34.4%, 31.9%, 39.5%和36.5%, 而序列数基本占据94%以上。相对丰度小于0.1%的OTU占总OTU数的80%。依次去除相对丰度低于0.01%至0.1%的OTU, 发现去除稀有OTU能够有效降低重复间差异, 去除越稀有的OTU, 降低效果越强; 对站位之间的差异影响较小, 且站位差异越大影响越小。稀有OTU的分布随机性极强, 基本与站位无关。相对丰度低于0.015%的OTU是造成重复间群落异质性的主要原因, 去除该部分OTU可更真实地展现底栖纤毛虫的群落异质性。 |
| 关键词: 海洋底栖纤毛虫 异质性 分子多样性 DNA高通量测序 稀有OTU |
| DOI：10.11759/hykx20201124002 |
| 分类号:Q958 |
| 基金项目:国家自然科学基金资助项目(41876171) |
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| Effect of rare OTUs on the community heterogeneity of marine benthic ciliates |
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ZHANG Yue1,2,3, ZHAO Feng2,3,4,5, SUN Meng-yan2,3,4, LI Yu-quan1, XU Kui-dong2,3,4,5
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1.Qingdao Agricultural University, Qingdao 266109, China;2.Department of Marine Organism Taxonomy &3.Phylogeny Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;4.University of Chinese Academy of Sciences, Beijing 100049, China;5.Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China
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| Abstract: |
| High-throughput sequencing always detects high heterogeneity among the replicates of protist communities, which is closely related to the extremely high proportion of rare operational taxonomic units (OTUs). The purpose of this study was to clarify the estimated community heterogeneity of benthic ciliates in relation to rare OTUs among replicates and to provide a threshold value for removing rare OTUs. Benthic ciliate diversity was estimated by performing high-throughput sequencing on three replicates obtained from four sites along environmental gradients in the continental shelf of the East China Sea. We found that community dissimilarities between replicates of each site ranged from 30% to 34%, higher than the dissimilarities between nearby sites. The proportion of OTUs shared by all three replicates at each site was 34.4%, 31.9%, 39.5%, and 36.5%, contributing to more than 94% of the total sequences. The rare OTUs, with a relative abundance of less than 0.1%, constituted over 80% of the total OTUs at each site. When OTUs with relative abundance less than the threshold of 0.01%–0.1% were removed, the community dissimilarity between replicates effectively decreased in a directly proportional manner. No other obvious change was detected in the community dissimilarity between sites, particularly in those with high community dissimilarity. The distribution of rare OTUs was extremely random and was independent of the variations in sites. Rare OTUs with a relative abundance below the threshold of 0.015% contributed the most to the community dissimilarity between replicates, and removing them helps improve the estimation of the community heterogeneity of marine benthic ciliates. |
| Key words: marine benthic ciliates heterogeneity molecular diversity high-throughput sequencing rare OTUs |
