Immigration reduces selection in water microbial community assembly

Area of Science:

• Microbial ecology
• Environmental microbiology
• Community assembly

Background:

• Understanding microbial community assembly is crucial for predicting ecosystem functions.
• Immigration and environmental selection are key factors influencing community structure.
• The role of dispersal in aquatic microbial communities requires further investigation.

Purpose of the Study:

• To investigate how immigration influences bacterial community assembly in aquatic ecosystems.
• To assess the impact of varying immigration rates on diversity, structure, and composition.
• To determine the relative importance of dispersal and environmental selection over time.

Main Methods:

• Community assembly experiment using outdoor microcosms with sterile water.
• Introduction of air particulate matter to simulate varying immigration rates.
• 16S rRNA gene amplicon sequencing to analyze bacterial community diversity and composition at early (13 days) and late (60 days) stages.

Main Results:

• Immigration did not significantly alter bacterial diversity at day 13 but increased it by day 60.
• Environmental selection's influence decreased significantly from day 13 to day 60.
• Dominant bacterial phyla shifted, and overall phyla richness increased substantially in later stages, indicating potential dispersal swamping.

Conclusions:

• Dispersal limitation plays a minimal role in early-stage aquatic bacterial community assembly.
• Increased immigration can weaken environmental selection, leading to dispersal swamping in later stages.
• The balance between dispersal and selection dynamically shapes microbial community assembly over time.