Large-scale metabarcoding analysis of epipelagic and mesopelagic copepods in the Pacific
Large-scale metabarcoding analysis of epipelagic and mesopelagic copepods in the Pacific
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DOI：
10.1371/journal.pone.0233189
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发表时间：
2020-05-14
期刊：
影响因子：
3.7
通讯作者：
Tsuda, Atsushi
中科院分区：
文献类型：
--
作者：
Hirai, Junya;Tachibana, Aiko;Tsuda, Atsushi
清楚地了解浮游桡足类的大规模群落结构对于理解海洋类群的多样性和生物地理学的控制机制至关重要，因为海洋类群的高丰度、普遍性和对环境变化的敏感性。在这里，我们对太平洋 70 个站和北冰洋 3 个站的上层和中层桡足类大型群落应用了 28S 元条形码方法。受水体结构影响的群落结构和多样性的主要模式与之前基于形态学的研究结果一致。然而，即使在稳定的环境条件下，大规模元条形码方法也可以检测群落变化，包括北/南亚热带环流以及每个亚热带环流内的东/西区域的变化。上层环境对中层群落有强烈的影响，并且在环境稳定的中层中观察到群落细分。在每个采样站中，中层中层的操作分类单元（OTU）数量均高于中层，而系统发育多样性低于表层，表明近期中层物种数量迅速增加。利用OTU代表序列的系统发育分析揭示了冷水OTU的近期出现趋势，冷水OTU主要分布在高纬度、低水温地区。相反，低纬度桡足类动物的高度多样性被认为是在高水温条件下经过长期进化而形成的。元条形码结果表明，进化过程对当前桡足类多样性模式产生了强烈影响，并支持解释桡足类纬度多样性梯度的“热带之外”理论。表层和中层桡足类的多样性模式与海面温度高度相关；因此，预测的全球变暖可能会对两层桡足类的多样性产生重大影响。
A clear insight into the large-scale community structure of planktonic copepods is critical to understanding the mechanisms controlling diversity and biogeography of marine taxa in terms of their high abundance, ubiquity, and sensitivity to environmental changes. Here, we applied a 28S metabarcoding approach to large-scale communities of epipelagic and mesopelagic copepods at 70 stations across the Pacific Ocean and three stations in the Arctic Ocean. Major patterns of community structure and diversity, influenced by water mass structures, agreed with results from previous morphology-based studies. However, a large-scale metabarcoding approach could detect community changes even under stable environmental conditions, including changes in the north/south subtropical gyres and east/west areas within each subtropical gyre. There were strong effects of the epipelagic environment on mesopelagic communities, and community subdivisions were observed in the environmentally stable mesopelagic layer. In each sampling station, higher operational taxonomic unit (OTU) numbers and lower phylogenetic diversity were observed in the mesopelagic layer than in the epipelagic layer, indicating a recent rapid increase in species numbers in the mesopelagic layer. The phylogenetic analysis utilizing representative sequences of OTUs revealed trends of recent emergence of cold-water OTUs, which are mainly distributed at high latitudes with low water temperatures. Conversely, the high diversity of copepods at low latitudes was suggested to have been formed through long evolution under high water temperature conditions. The metabarcoding results suggest that evolutionary processes have strong impacts on current patterns of copepod diversity, and support the "out of the tropics" theory explaining latitudinal diversity gradients of copepods. Diversity patterns in both epipelagic and mesopelagic copepods was highly correlated to sea surface temperature; thus, predicted global warming may have a significant impact on copepod diversity in both layers.