中国亚热带-热带3个海区微型鞭毛虫群落优势种和稀有种的分布特征和建群机制

海洋微型鞭毛虫是海洋微型真核浮游生物中非常重要的一大类群，在构成和维持海洋生态系统的结构和功能中扮演着重要角色。微生物群落通常由少数优势种和大量稀有种组成，这种分布模式在海洋微型鞭毛虫群落中也极为常见，并且二者的内在特征可能对群落生物地理分布格局以及生态系统功能产生不同影响。然而在多数研究中并未将两种不同亚群落进行区分，对二者的分布特征、对环境和空间因子的响应以及在总体群落中的生态地位等的认识十分有限。本研究利用高通量测序技术，调查了中国近海亚热带-热带3个自然海区微型鞭毛虫群落中优势种和稀有种的分布特征，并探讨了环境因子和空间因子与不同亚群落之间的关系，利用中性模型揭示了中性过程在群落构建中的作用，最后通过共现网络分析解析了两种不同亚群落在总体群落中的生态地位。结果表明：3个海区微型鞭毛虫群落中的优势类群和稀有类群在多样性和物种组成上具有不同的特征，表现出一定的生物地理分布格局；这与它们受到不同程度环境因子和空间因子的驱动作用有关；中性模型的结果体现了随机过程在两种亚群落中的重要作用；最后，共现网络关系反映出不同丰富程度的生态类群具有重叠但又相异的生态位，从而在同一环境中形成物种的共...

Distribution patterns and assembly mechanisms of dominant and rare species of microbial flagellate communities in the subtropic-tropic marine areas in China

Marine microbial flagellates are a very important group of microbial eukaryotes that play essential roles in the structure and function of marine ecosystems. Microbial communities are usually composed of a few dominant species and many rare species, of which the distribution pattern is also very common in marine microbial flagellate communities. Their inherent characteristics may have different effects on the community biogeographic distribution pattern and ecosystem functions. However, the two different sub-communities were not distinguished in most studies, and the understanding of their distribution patterns, response to environmental and spatial factors, and ecological status in the overall community was very limited. This study conducted high-throughput sequencing of eukaryotic 18S rRNA gene V4 region to comprehensively investigate the distribution characteristics of dominant and rare species in the microbial flagellate communities in 3 subtropic-tropic marine areas in China. The relationships between both environmental and spatial factors and two subcommunities were also explored. The neutral model was used to reveal the importance of neutral process in community assembly. Finally, the ecological status of two sub-communities in the overall community was compared using co-occurrence network analysis. The results showed different characteristics in diversity and species composition of the dominant and rare sub-communities in the 3 sea areas, which led to comparable biogeographic distribution patterns. This was related to the different degrees of the driving effects of environmental and spatial factors on different sub-communities. The neutral model reflected the important role of the neutral process in the two su-bcommunities. Finally, the cooccurrence network revealed the overlapping but different niches of the two sub-communities, which formed coexistence of species and thus maintained the community stability. Among these, the rare taxa, with a higher degree of connectivity and a higher proportion of the number of keystones species, played important roles in the network. Overall, the findings of this study revealed the distribution patterns and community assembly mechanisms of dominant and rare species of microbial flagellates in the coastal waters of China, and provided a theoretical basis for further understanding of the community structure, biogeographic distributions, and ecological processes of marine microbial flagellate communities.