Guangdong Provincial Key Laboratory of Water Quality Improvement and Ecological Restoration for Watersheds, Institute of Environmental and Ecological Engineering, Guangdong University of Technologygrid.411851.8, Guangzhou, Guangdong, China.
Key Laboratory of Water and Sediment Sciences of Ministry of Education/State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal Universitygrid.20513.35, Beijing, Hebei, China.
Appl Environ Microbiol. 2022 Jun 28;88(12):e0059722. doi: 10.1128/aem.00597-22. Epub 2022 May 31.
Bacterial biodiversity is tightly correlated with ecological functions of natural systems, and bacterial rare and abundant subcommunities make distinct contributions to ecosystem functioning. However, the biogeographic pattern and elevational differentiation of sedimentary bacterial diversity have rarely been studied in cross-river systems at a continental scale. This study analyzed the biogeographic patterns and elevational differentiations of the entire, abundant, and rare bacterial (sub)communities as well as the underlying mechanisms across nine rivers that span distinct geographic regions and large elevational gradients in China. We found that bacterial rare and abundant subcommunities shared similar biogeographic patterns and both demonstrated strong distance-decay relationships, despite their distinct community compositions. However, both null model and variation partitioning analysis results showed that while environmental selection governed rare subcommunity assemblies (contribution: 51.9%), dispersal limitation (62.7%) controlled the assembly of abundant subcommunities. The disparity was associated with the broader threshold width of abundant taxa to water temperature and pH variations than rare taxa. Elevation-induced bacterial composition variations were more evident than latitude-induced ones. Some specific operational taxonomic units (OTUs), representing 16.4% of the total sequences, much preferentially and even exclusively lived in high-elevation or low-elevation habitats and demonstrated some adaptations to local conditions. Greater positive: negative link ratios in bacterial co-occurrence networks of low elevations than high elevations (0.05) partly resulted from their harboring higher organic carbon: nitrogen ratios. Together, this study draws a biogeographic picture of sedimentary bacterial communities in a continental-scale riverine system and highlights the importance of incorporating elevation-associated patterns of microbial diversity into riverine microbial ecology studies. Bacterial diversity is tightly correlated with the nutrient cycling of river systems. However, previous studies on bacterial diversity are mainly constrained to one single river system, although microbial biogeography and its drivers exhibit strong spatial scale dependence. Moreover, elevational differentiations of bacterial communities across river systems have also rarely been studied. Bacterial rare and abundant subcommunities make distinct contributions to ecosystem functioning, and they share similar biogeographic patterns in some environments but not in others. Therefore, we explored the biogeography of the entire, abundant, and rare (sub)communities in nine rivers that cover a wide space range and large elevational gradient in China. Our results revealed that bacterial rare and abundant subcommunities shared similar biogeographic patterns but their assembly mechanisms were much different in these rivers. Moreover, bacterial communities showed evident differentiations between high elevations and low elevations. These findings will facilitate a better understanding of bacterial diversity features in river systems.
细菌生物多样性与自然系统的生态功能密切相关，细菌稀有和丰富亚群落对生态系统功能有显著贡献。然而，在大陆尺度的跨河系统中，很少有研究涉及沉积物细菌多样性的生物地理格局和海拔分异。本研究分析了中国 9 条河流横跨不同地理区域和大海拔梯度的整个、丰富和稀有（亚）群落的生物地理格局和海拔分异以及潜在机制。我们发现，尽管细菌稀有和丰富亚群落的群落组成不同，但它们具有相似的生物地理格局，并且都表现出强烈的距离衰减关系。然而，无论是零模型还是变异划分分析结果都表明，尽管环境选择控制了稀有亚群落的组装（贡献：51.9%），但扩散限制（62.7%）控制了丰富亚群落的组装。这种差异与丰富类群对水温和 pH 变化的更广泛的阈值宽度有关，而稀有类群则较窄。海拔引起的细菌组成变化比纬度引起的变化更为明显。一些特定的操作分类单元（OTUs），代表总序列的 16.4%，更偏好甚至专门生活在高海拔或低海拔生境中，并表现出对当地条件的一些适应。低海拔细菌共生网络中的正：负连接比率大于高海拔（0.05），部分原因是它们含有较高的有机碳：氮比。总之，本研究描绘了大陆尺度河网系统中沉积物细菌群落的生物地理图景，并强调了将与海拔相关的微生物多样性模式纳入河网微生物生态学研究的重要性。细菌多样性与河流系统的养分循环密切相关。然而，尽管微生物生物地理学及其驱动因素具有很强的空间尺度依赖性，但以前关于细菌多样性的研究主要局限于一个单一的河流系统。此外，跨河系统的细菌群落的海拔分异也很少被研究。细菌稀有和丰富亚群落对生态系统功能有显著贡献，并且在某些环境中它们具有相似的生物地理格局，但在其他环境中则不然。因此，我们探索了中国 9 条河流的整个、丰富和稀有（亚）群落的生物地理学，这些河流覆盖了广泛的空间范围和大的海拔梯度。我们的结果表明，细菌稀有和丰富亚群落具有相似的生物地理格局，但它们在这些河流中的组装机制却大不相同。此外，细菌群落在高海拔和低海拔之间表现出明显的差异。这些发现将有助于更好地理解河流系统中的细菌多样性特征。
