Abstract

Methanogenesis from oxic water has been proven to be a significant component of methane source in large and deep freshwater ecosystems. However, the biogeography of methanogenic community in surface water of large rivers remains uncertain. Here, the community ecology and biogeographic pattern of methanogenic community along the Yangtze River (one of the largest rivers in the world) were studied by using high-throughput sequencing, and the relative importance of environmental and spatial variables on the assemblage of methanogenic community was assessed. The results showed a distinct spatial distribution that the Shannon diversity and Shannon evenness of methanogenic community in downstream of the Yangtze River were significantly higher than those in upstream and midstream sections. The most abundant three genera of methanogenic community were Methanobacterium, Methanosarcina and Methanosaeta, which did not exhibit significant difference between different sections. Besides, the composition of methanogenic community also showed a clear spatial variation along the river. Significant distance effects appeared on both methanogenic community and environmental variables. However, no significant relationship was found between methanogenic community and environmental variables. Compared to the limited contributions of spatial and environmental variables, interactions among taxa could be an important driver in structuring the assembly of methanogenic community. In addition, Methanobacteriales, Methanomassiliicoccales and Methanocellales were the key species of methanogenic community in upstream, midstream and downstream sections, respectively. Overall, the methanogenic community exhibited obvious biogeographic pattern along the Yangtze River, which was attributed to a joint effect of abiotic and biotic factors.

摘要

已证明含氧水的产甲烷作用是大型深层淡水生态系统中甲烷来源的重要组成部分。然而，大型河流地表水中产甲烷群落的生物地理学仍不确定。在此，利用高通量测序研究了长江（世界上最大的河流之一）沿岸产甲烷群落的群落生态和生物地理格局，并研究了环境和空间变量对产甲烷群落组合的相对重要性。评估。结果表明，长江下游产甲烷群落的香农多样性和香农均匀度明显高于上游和中游段的空间分布。产甲烷菌群落最丰富的三个属是Methanobacterium , Methanosarcina和Methanosaeta，在不同切片之间没有表现出显着差异。此外，沿河产甲烷群落的组成也呈现明显的空间变化。产甲烷群落和环境变量均出现显着的距离效应。然而，未发现产甲烷群落与环境变量之间存在显着关系。与空间和环境变量的有限贡献相比，分类群之间的相互作用可能是构建产甲烷群落组装的重要驱动因素。此外，Methanobacteriales，Methanomassiliicoccales和Methanocellales分别是上游、中游和下游部分产甲烷群落的关键物种。总体而言，长江沿岸产甲烷群落表现出明显的生物地理格局，这是非生物和生物因素共同作用的结果。