Higher Contribution of Generalists Than Specialists to the Bacterial Biogeography Across Lakes in Northern China

Aim

Given that microbial communities normally comprise generalist and specialist species, there have been limited efforts to estimate the contribution of these sub-communities to bacterial biogeography regarding ecological assembly processes and nestedness structure. To resolve this gap, we studied the spatial distribution of bacterioplankton communities and their generalist and specialist sub-communities, as well as the underlying assembly processes.

Location

Six lakes span three climate zones in northern China.

Time Period

September 2021.

Methods

By separately analysing the generalist and specialist sub-communities from the whole communities, we investigated the relationships between sub-communities and the entire communities in terms of distance-decay pattern, nestedness, and assembly processes. As such, we assessed the contribution of generalist and specialist sub-communities to the biogeographic patterns of the whole communities.

Major Taxa Studies

Bacterial community.

Results

Generalist sub-communities were more diverse but less abundant than specialist sub-communities. In line with the whole communities, both types of sub-communities exhibited distance-decay relationships at the regional scale, with the slope of specialists being steeper than that of generalists. Additionally, generalist sub-communities and whole communities also exhibited similar nestedness patterns, in which assemblages from saline water were the subset of those from freshwater. In terms of assembly processes, generalist sub-communities and whole communities were strongly regulated by homogeneous selection, whereas specialist sub-communities were mainly shaped by dispersal limitation. More importantly, there was a transition from stochastic to deterministic assembly processes for generalist sub-communities and whole communities and generalist sub-communities with increasing total dissolved solids.

Main Conclusions

Relative to the specialists, the assembly processes and nestedness pattern were more altered if the generalists were absent, which implies the higher contribution of generalist sub-communities on the biogeography of whole communities at the regional scale.