5. Conclusions
In summary, the present study systematically investigated the biogeographic patterns, environmental adaptations, assembly processes, and co-occurrence patterns of abundant and rare bacteria in the sediments of the Yarlung Tsangpo River. The present work linked abundant and rare bacterial community traits, including phylogenetic clustering, environmental thresholds, and phylogenetic signals of ecological preferences to different environmental conditions, and revealed the factors mediating community assembly processes. We found that abundant taxa had stronger environmental adaptation and exhibited ubiquitous distribution, whereas rare taxa were more sensitive to environmental changes and exhibited restricted distribution. Forest area and TN were the major factors mediating the balance of stochastic and deterministic assembly processes in the abundant and rare subcommunities, respectively. Although the rare taxa were less connected and located more peripherally within the co-occurrence network compared with abundant taxa, both played important roles in maintaining network stability. These results expand our understanding of the mechanisms underlying the maintenance of microbial diversity and predicting microbial responses to environmental perturbation caused by climate change and human activities in the Yarlung Tsangpo River.