Dispersal shapes compositional and functional diversity in aquatic microbial communities.

Area of Science:

• Microbial ecology
• Community assembly dynamics
• Aquatic microbial ecosystems

Background:

• Dispersal (segregation and mixing) influences aquatic microbial community structure and function.
• Disentangling these roles in field studies is challenging.
• Experimental approaches are needed to understand dispersal impacts.

Purpose of the Study:

• To experimentally assess the effects of dispersal limitation and homogenizing dispersal on freshwater bacterial assemblages.
• To investigate how these dispersal regimes impact community composition, beta diversity, and functional properties.
• To understand the role of dispersal in regulating metacommunity diversity and function.

Main Methods:

• Examined 20 freshwater bacterial assemblages under identical conditions for 34 days (seven growth cycles).
• Subjected assemblages to two consecutive dispersal regimes: dispersal limitation and homogenizing dispersal.
• Analyzed compositional and functional changes, including beta diversity and carbon use efficiency.

Main Results:

• Dispersal limitation increased beta diversity and functional variability, leading to distinct community types.
• Homogenizing dispersal resulted in high compositional similarity and reduced gamma diversity.
• Community assembly was largely explained by neutral and competition-based models, with a dominant pseudomonad.
• Segregation protected competitively weak but productive taxa.

Conclusions:

• Stochastically generated microbial assemblages can be refined into distinct types by deterministic processes.
• Dispersal is crucial in regulating microbial metacommunity diversity and functional variability.
• Findings provide insights for predicting changes in aquatic ecosystem functioning.