Rare bacterial biosphere is more environmental controlled and deterministically governed than abundant one in sediment of thermokarst lakes across the Qinghai-Tibet Plateau

Abstract

Thermokarst lakes are widely distributed in cold regions as a result of ice-rich permafrost thaw. Disentangling the biogeography of abundant and rare microbes is essential to understanding the environmental influences, assembly mechanisms, and responses to climate change of bacterial communities in thermokarst lakes. In light of this, we assessed the abundant and rare bacterial subcommunities in sediments from thermokarst lakes across the Qinghai-Tibet Plateau (QTP). The operational taxonomic unit (OTU) richness was more strongly associated with location and climate factors for abundant subcommunities, while more strongly associated with physicochemical variables for rare subcommunities. The relative abundance of abundant and rare taxa showed opposite patterns with abundant taxa having greater relative abundance at higher latitude and pH, but at lower mean annual precipitation and nutrients. Both the abundant and rare subcommunities had a clear distribution pattern along the gradient of latitude and mean annual precipitation. Abundant subcommunities were dominantly shaped by dispersal limitation processes (80.9%), while rare subcommunities were shaped almost equally by deterministic (47.3%) and stochastic (52.7%) processes. The balance between stochastic and deterministic processes was strongly environmentally adjusted for rare subcommunities, while not associated with environmental changes for abundant subcommunities. The results shed light on biogeography patterns and structuring mechanisms of bacterial communities in thermokarst lakes, improving our ability to predict the influences of future climate change on these lakes.

Biogeographic Patterns of Fungal Sub-Communities under Different Land-Use Types in Subtropical China

“…The higher community diversity of rare and intermediate taxa encouraged a shift toward stochastic processes of community assembly. However, the variation in diversity of abundant taxa showed opposite results to those of rare and intermediate taxa, but the assembly process realized a similar trend, probably related to the high environmental adaptability of abundant taxa [ 44 , 68 ].…”

Different responses of abundant and rare bacterial composition to groundwater depth and reduced nitrogen application in summer maize field

“…The rare and abundant OTUs were defined following previous study ( Jiao and Lu, 2020b ; Wan et al, 2021 ). OTUs with a relative abundance of >0.1% of the total abundance were defined as abundant bacteria, and rare bacteria were those with a relative abundance of <0.01% ( Mo et al, 2018 ; Wang et al, 2021b ; Ren et al, 2022 ).…”

Carbon‐cycling microorganisms in permafrost and their responses to a warming climate: A review

“…On the other hand, community variations are also influenced by stochastic processes, such as dispersal limitation and drift, and the drift effect can be intensified by lower biomass and richness 91,92 . For example, rare microbial consortia from thermokarst lakes on the QTP displayed a stronger association with the environment compared with abundant microbial groups 93 . The emergence of stable environments leads to stable levels of deterministic selection, while higher disturbance can impose a variable selection scenario 90 .…”

“…91,92 For example, rare microbial consortia from thermokarst lakes on the QTP displayed a stronger association with the environment compared with abundant microbial groups. 93 The emergence of stable environments leads to stable levels of deterministic selection, while higher disturbance can impose a variable selection scenario. 90 A dominance of deterministic processes has been widely observed over various landscapes.…”