Chen Juan, Wang Peifang, Wang Chao, Wang Xun, Miao Lingzhan, Liu Sheng, Yuan Qiusheng, Sun Shenghao
Key Laboratory of Integrated Regulation and Resource Department on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, China.
Front Microbiol. 2020 Feb 7;11:158. doi: 10.3389/fmicb.2020.00158. eCollection 2020.
Bacterioplankton communities commonly consist of few highly abundant species and a large number of rare species that play key roles in biogeochemical cycles of aquatic ecosystems. However, little is known about the biogeographic assemblies of these communities, especially in large rivers suffering from cascade dam regulation. Here, we used a gene amplicon sequencing approach to investigate the biogeographic patterns and underlying assembly mechanisms of abundant and rare bacterioplankton taxa in cascade reservoirs of the Jinsha River in China. The results revealed species loss of bacterioplankton due to dam construction, which was more significant for rare taxa than for abundant ones. The distributions of abundant and rare taxa exhibited similar spatial and temporal patterns, which were significantly distinct between winter and summer and between upstream and downstream reservoirs. Both spatial (dispersal-related process) and environmental (selection process) factors seemed to together govern the assembly and biogeography of abundant and rare taxa, although both factors explained only a small fraction of variation in the rare taxa. More importantly, environmental factors explained more community variation in abundant sub-community than that in rare sub-community. Co-occurrence network analysis revealed that abundant species with closer interactions were more often located in a central position of the network compared with rare species. Nevertheless, half of the keystone species were rare species and may play important roles in maintaining the network stability. Overall, these findings indicate that distinct assembly mechanisms underlie the similar biogeography of rare and abundant bacteria in cascade reservoirs of a large river.
浮游细菌群落通常由少数高丰度物种和大量稀有物种组成，这些稀有物种在水生生态系统的生物地球化学循环中发挥着关键作用。然而，对于这些群落的生物地理组装情况，我们知之甚少，尤其是在受梯级大坝调控影响的大型河流中。在此，我们采用基因扩增子测序方法，研究了中国金沙江梯级水库中丰度和稀有度不同的浮游细菌类群的生物地理模式及其潜在的组装机制。结果表明，大坝建设导致浮游细菌物种丧失，稀有类群的物种丧失比丰度类群更为显著。丰度类群和稀有类群的分布呈现出相似的时空模式，冬季和夏季之间以及上游和下游水库之间存在显著差异。空间（与扩散相关的过程）和环境（选择过程）因素似乎共同控制着丰度类群和稀有类群的组装及生物地理学，尽管这两个因素仅解释了稀有类群中一小部分变异。更重要的是，环境因素对丰度亚群落的群落变异解释比对稀有亚群落的解释更多。共现网络分析表明，与稀有物种相比，具有更紧密相互作用的丰度物种更常位于网络的中心位置。然而，半数关键物种是稀有物种，它们可能在维持网络稳定性方面发挥重要作用。总体而言，这些发现表明，大型河流水库中稀有和丰度细菌相似的生物地理学背后存在不同的组装机制。
