The photic‐aphotic divide is a strong ecological and evolutionary force determining the distribution of ciliates (Alveolata, Ciliophora) in the ocean
The photic‐aphotic divide is a strong ecological and evolutionary force determining the distribution of ciliates (Alveolata, Ciliophora) in the ocean
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DOI：
10.1111/jeu.12976
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发表时间：
2023-04
影响因子：
2.2
通讯作者：
L. Santoferrara;Aleena Qureshi;Amina Sher;L. Blanco-Bercial
中科院分区：
文献类型：
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作者：
L. Santoferrara;Aleena Qureshi;Amina Sher;L. Blanco-Bercial
关于海洋纤毛虫的大部分知识来自浅水和/或阳光照射的沃茨。我们研究了纤毛虫的多样性和分布在表层和中层海洋沃茨，使用DNA元条形码和基于遗传学的指标。我们分析了18 S rRNA基因（V4区）的序列，从369个样本收集在12个深度（0-1000米）在百慕大大西洋时间序列研究网站的马尾藻海（北大西洋）每月3年。全面的深度和时间分辨率分析导致三个主要结果。首先，从水面到1000米沃茨，α多样性（基于费思的系统发育多样性指数）逐渐但显著减少。其次，β多样性的多变量分析（基于UniFrac距离）表明，纤毛虫组合从透光到无光沃茨发生显着变化，从Oligotrichea到Oligohyophyphorea流行。第三，序列变异的系统发育位置和进化枝水平的相关性（EPA-ng和GAPPA算法）显示寡毛纲（Oligotrichea）、Litostomatea、Prostomatea和Phyllopharyngea与深度呈反相关，而寡水藓纲（Oligohyphyphyphorea）（特别是Apostomatia）与深度有直接关系。两个神秘的环境分支包括广泛分布在无光层（Oligohyphorea OLIGO 5）或亚分支差异分布在光与无光沃茨（Discotrichidae NASSO 1）的流行变种。这些结果解决了之前报道的纤毛虫α多样性和深度之间的矛盾关系，表明从透光到无光沃茨的纤毛虫组合的功能变化（分别为藻类和混合营养与杂食性和寄生性的流行），并表明当代分类群在垂直剖面中的分布受到进化过程的强烈影响。整合DNA序列与有机体数据（显微镜，功能实验）和数据库的发展，这些信息来源的链接仍然是主要任务，以更好地了解纤毛虫的多样性，生态作用，在海洋中的进化。
The bulk of knowledge on marine ciliates is from shallow and/or sunlit waters. We studied ciliate diversity and distribution across epi‐ and mesopelagic oceanic waters, using DNA metabarcoding and phylogeny‐based metrics. We analyzed sequences of the 18S rRNA gene (V4 region) from 369 samples collected at 12 depths (0–1000 m) at the Bermuda Atlantic Time‐series Study site of the Sargasso Sea (North Atlantic) monthly for 3 years. The comprehensive depth and temporal resolutions analyzed led to three main findings. First, there was a gradual but significant decrease in alpha‐diversity (based on Faith's phylogenetic diversity index) from surface to 1000‐m waters. Second, multivariate analyses of beta‐diversity (based on UniFrac distances) indicate that ciliate assemblages change significantly from photic to aphotic waters, with a switch from Oligotrichea to Oligohymenophorea prevalence. Third, phylogenetic placement of sequence variants and clade‐level correlations (EPA‐ng and GAPPA algorithms) show Oligotrichea, Litostomatea, Prostomatea, and Phyllopharyngea as anti‐correlated with depth, while Oligohymenophorea (especially Apostomatia) have a direct relationship with depth. Two enigmatic environmental clades include either prevalent variants widely distributed in aphotic layers (the Oligohymenophorea OLIGO5) or subclades differentially distributed in photic versus aphotic waters (the Discotrichidae NASSO1). These results settle contradictory relationships between ciliate alpha‐diversity and depth reported before, suggest functional changes in ciliate assemblages from photic to aphotic waters (with the prevalence of algivory and mixotrophy vs. omnivory and parasitism, respectively), and indicate that contemporary taxon distributions in the vertical profile have been strongly influenced by evolutionary processes. Integration of DNA sequences with organismal data (microscopy, functional experiments) and development of databases that link these sources of information remain as major tasks to better understand ciliate diversity, ecological roles, and evolution in the ocean.