Top-Down and Bottom-Up Controls on Microeukaryotic Diversity (i.e., Amplicon Analyses of SAR Lineages) and Function (i.e., Metatranscriptome Analyses) Assessed in Microcosm Experiments
Top-Down and Bottom-Up Controls on Microeukaryotic Diversity (i.e., Amplicon Analyses of SAR Lineages) and Function (i.e., Metatranscriptome Analyses) Assessed in Microcosm Experiments
复制标题
DOI：
10.3389/fmars.2019.00818
复制
发表时间：
2020-01
期刊：
影响因子：
--
通讯作者：
Jean-David Grattepanche;L. Katz
中科院分区：
文献类型：
--
作者：
Jean-David Grattepanche;L. Katz
高通量测序（HTS）的可用性已经改变了我们对微生物真核生物多样性的理解（即，原生生物）在不同的栖息地。然而，将这种生物多样性与功能联系起来仍然是一个挑战，特别是在微生物食物网的背景下。在这里，我们进行了一组微观实验，以评估不断变化的捕食者和猎物的浓度对海洋原生生物群落的影响，专注于SAR（Stravelila，Alveolata，Rhizaria）谱系。我们结合联合收割机的分类多样性的估计，通过分析的SSU-rDNA扩增与元转录组学，代理功能。我们评估了从新英格兰沃茨取样的一个群落的变化，该群落具有不同浓度的捕食者（桡足类）和猎物（尺寸小于15 μm的浮游植物）。观察到的最大影响是在猎物丰度高的情况下对小型浮游生物（2-10 μm，微型浮游生物）群落的多样性和功能的影响（即，起霜条件）。许多SAR分类群的纳米级部分减少浮游植物丰度的增加，而纤毛虫（从纳米级和微米级部分）增加。在我们模拟的浮游植物水华期间，大量的转录本和功能估计在微型浮游生物减少。我们还发现了浮游植物和桡足类丰度的增加之间的相互作用的微型浮游生物群落的证据，与浮游植物和桡足类施加自下而上的控制和自上而下的控制微型原生生物的假设相一致，分别。我们的分析表明，社区功能[即，基因家族（GF）的多样性]保持相对稳定，而在物种水平上的功能（即，GF内的转录物多样性）在水华条件下显示出功能的显著降低。我们的研究表明，浮游生物食物网内的相互作用是复杂的，海洋微真核生物的多样性和功能之间的关系仍然知之甚少。
The availability of high-throughput sequencing (HTS) has transformed our understanding of the diversity of microbial eukaryotes (i.e., protists) across diverse habitats. Yet relating this biodiversity to function remains a challenge, particularly in the context of microbial food webs. Here we perform a set of microcosm experiments to evaluate the impact of changing predator and prey concentrations on a marine protist community, focusing on SAR (Stramenopila, Alveolata, and Rhizaria) lineages. We combine an estimate of taxonomic diversity through analysis of SSU-rDNA amplicons with metatranscriptomics, a proxy for function. We assess changes in a community sampled from New England waters with varying concentrations of predators (copepods) and prey (phytoplankton <15 μm in size). The greatest impact observed is on the diversity and function of the small plankton (2–10 μm, nanoplankton) community in the presence of high prey abundance (i.e., bloom conditions). Many SAR taxa in the nanosized fraction decrease with increasing phytoplankton abundance, while ciliates (from both the nano- and microsized fractions) increase. A large number of transcripts and function estimates in the nanoplankton decreased during our simulated phytoplankton bloom. We also find evidence of an interaction between increasing phytoplankton and copepod abundances on the microsized planktonic community, consistent with the hypothesis that phytoplankton and copepods exert bottom-up control and top-down control on the microsized protists, respectively. Together our analyses suggest that community function [i.e., diversity of gene families (GFs)] remains relatively stable, while the functions at the species level (i.e., transcript diversity within GFs) show a substantial reduction of function under bloom conditions. Our study demonstrated that interactions within plankton food webs are complex, and that the relationships between diversity and function for marine microeukaryotes remain poorly understood.