Assembly Processes and Co-occurrence Patterns of Abundant and Rare Bacterial Community in the Eastern Indian Ocean

Abstract

Microbial communities are composed of many rare species and a few abundant species. Considering the disproportionate importance of rare species for ecosystem functioning, it is important to understand the mechanisms structuring the rare and abundant components of a diverse community in response to environmental changes. Here, we used a 16S ribosomal RNA gene sequencing approach to investigate the bacterial community diversity in the Eastern Indian Ocean (EIO) during the monsoon and intermonsoon. We employed a phylogenetic null model and network analysis to evaluate the assembly processes and co-occurrence pattern of the microbial community. We found that higher bacterial diversity was detected in the intermonsoon with high temperature and low Chlorophyll a concentrations and N/P ratios. The balance between ecological deterministic processes and stochastic processes varied with seasons in the EIO. Meanwhile, conditionally rare taxa (CRT) were more likely modulated by variable selection processes than always rare taxa (ART) and abundant taxa (AT) (CRT > ART > AT). By linking assembly process and species co-occurrence, we demonstrated that the microbial co-occurrence associations tended to be higher when deterministic processes (mainly variable selection) were weaker. This negative trend was observed in rare species rather than abundant species. The linkage could enhance our understanding of the underlying mechanisms underpinning the generation and maintenance of microbial community diversity.

Integrating Stochastic and Deterministic Process in the Biogeography of N2-Fixing Cyanobacterium Candidatus Atelocyanobacterium Thalassa

“…Sea surface temperature and salinity were determined and recorded using a conductivity–temperature–depth (CTD) system on board (Seabird SBE 911Plus, Sea-Bird Electronics, WA, United States). Sample analysis for other physicochemical parameters, such as inorganic nutrients and Chlorophyll a (Chl a ), were consistent with our previous work ( Wu et al, 2019 ; Li et al, 2021b ). Briefly, we used 100-ml PE bottles to collect seawater for nutrient analysis.…”

Comparison of assembly process and co-occurrence pattern between planktonic and benthic microbial communities in the Bohai Sea

“…By constructing the linkage between assembly processes and species co-occurrence in microbial communities, Jiao et al (2020) found that the microbial co-occurrences tended to be higher when agricultural soil microbial communities were mainly driven by dispersal limitation. By contrast, Li et al (2021a) found that deterministic processes (mainly heterogeneous selection) became a less dominant ecological process in the intermonsoon communities in the Eastern Indian Ocean as the co-occurrence increased. These linkages were thought to be largely related to environmental filtering ( Jiao et al, 2020 ; Li et al, 2021a ).…”

“…By contrast, Li et al (2021a) found that deterministic processes (mainly heterogeneous selection) became a less dominant ecological process in the intermonsoon communities in the Eastern Indian Ocean as the co-occurrence increased. These linkages were thought to be largely related to environmental filtering ( Jiao et al, 2020 ; Li et al, 2021a ). In this study, an opposite trend was observed that stochastic processes become less dominant as the connection of microbial communities increased.…”

“…Determining the linkages between community assembly and species coexistence is essential to understand the mechanisms that maintain community diversity ( Vályi et al, 2016 ; Jiao et al, 2020 ; Li et al 2021a ). By constructing the linkage between assembly processes and species co-occurrence in microbial communities, Jiao et al (2020) found that the microbial co-occurrences tended to be higher when agricultural soil microbial communities were mainly driven by dispersal limitation.…”

“…For example, environmental factors (deterministic processes) including temperature, salinity, and sand size exerted a stronger influence than spatial factors (stochastic processes) on the benthic microeukaryotic communities in marine sandy beaches (up to 12,000 km; Zhang et al, 2018 ), whereas stochastic processes were the most important process in the assembly of archaeal communities in coastal sediments from the eastern Chinese marginal seas (up to 1,500 km; Liu et al, 2020 ). These studies suggest that the assembly of microbial community are not conserved among various ecosystems, emphasizing the importance for comparative analyses between environments ( Allen et al, 2020 ; Li et al, 2021a ).…”