Discussion
Identifying the interactions between bacteria and microeukaryotes and the combination of complex ecological communities is critical for the management of biodiversity, especially in areas with strong human interference and fragile ecosystems. OTUs belonging to keystone taxa are nodes with the low betweenness centrality values and high degree, which are very significant for maintaining the stability of the ecosystem (Ma et al., 2016). Regarding microbial communities, several hypotheses have been proposed, including ”neutral theory” and ”niche theory” (Dumbrell, Nelson, Helgason, Dytham, & Fitter, 2010). The Neutral theory predicts that community structure and composition are relevant to the geographic distance between samples, which is due to the dispersal restrictions, because many species have equal functions in the ability to utilize niche. The niche theoretical predicts that changes in species community composition are related to variations in environmental parameters (Jongman, Ter Braak, & Van Tongeren, 1995), because species have unique characteristics that enable them to develop unique habitats that can be used. Here, we pointed out the functional roles and environmental variables associated with keystone species. By looking for related changes in the abundance of natural taxa and ecosystem functions, we can infer which processes are important.