This data-intensive study investigated the delicate balance of niche and neutrality underlying microbial communities in freshwater ecosystems through comprehensive application of high-throughput sequencing, species abundance distribution (SAD), and the neutral community model (NCM), combined with species diversity and phylogenetic measures, which unite the traditional and microbial ecology. On the genus level, 45.10% and 41.18% of the water samples could be explained by the log-normal and Volkov model respectively, among which 31.37% could fit both models. Meanwhile, 55.56% of the sediment samples could be depicted by the log-normal model, and Volkov-fitted samples comprised only 13.33%. Besides, operational taxonomic units (OTUs) from water samples fit Sloan's neutral model significantly better than those in sediment. Therefore, it was concluded that deterministic processes played a great role in both water and sediment ecosystems, whereas neutrality was much more involved in water assemblages than in non-fluidic sediment ecosystems. Secondly, log-normal fitted samples had lower phylogenetic species variability (PSV) than Volkov-fitted ones, indicating that niche-based communities were more phylogenetically clustered than neutrally assembled counterparts. Additionally, further testing showed that the relative richness of rare species was vital to SAD modeling, either niche-based or neutral, and communities containing fewer rare species were more easily captured by theoretical SAD models.

中文翻译：

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生态位和中性在流体和非流体生态系统中的微生物群落中的作用不同。

这项数据密集型研究通过全面应用高通量测序，物种丰度分布（SAD）和中性群落模型（NCM），结合物种多样性和系统发育，研究了淡水生态系统中微生物群落的生态位和中性之间的微妙平衡。措施，将传统和微生物生态相结合。在属水平上，可用对数正态和沃尔科夫模型分别解释45.10％和41.18％的水样，其中31.37％可以拟合这两种模型。同时，对数正态模型可以描述55.56％的沉积物样品，而Volkov拟合的样品仅占13.33％。此外，水样本中的操作分类单位（OTU）比斯隆的中立模型要好得多。因此，结论是，确定性过程在水和沉积物生态系统中都起着重要作用，而中性比非流动性沉积物生态系统更多地参与水的组合。其次，对数正态拟合样本的系统发育物种变异性（PSV）比Volkov拟合样本的系统变异性低，这表明基于利基的群落比中性组装的种群在系统发育上更为聚类。此外，进一步的测试表明，稀有物种的相对丰富度对于基于生态位或中性的SAD建模至关重要，并且理论SAD模型更容易捕获包含较少稀有物种的社区。相较于非流态沉积物生态系统，水组合中的中性更多。其次，对数正态拟合样本的系统发育物种变异性（PSV）比Volkov拟合样本的系统变异性低，这表明基于利基的群落比中性组装的种群在系统发育上更为聚类。此外，进一步的测试表明，稀有物种的相对丰富度对于基于生态位或中性的SAD建模至关重要，并且理论SAD模型更容易捕获包含较少稀有物种的社区。相较于非流态沉积物生态系统，水组合中的中性更多。其次，对数正态拟合样本的系统发育物种变异性（PSV）比Volkov拟合样本的系统变异性低，这表明基于利基的群落比中性组装的种群在系统发育上更为聚类。另外，进一步的测试表明，稀有物种的相对丰富度对于基于生态位或中性的SAD建模至关重要，并且理论上的SAD模型更容易捕获包含较少稀有物种的社区。