Linking stochastic assembly to functional potential, redundancy, and trait patterns in bacterial communities.

Area of Science:

• Microbial ecology
• Community assembly
• Metagenomics

Background:

• Stochastic processes influence microbial community composition but their effect on function is debated due to redundancy.
• The relationship between stochasticity and functional redundancy is poorly understood.
• This study investigates how stochastic assembly impacts functional redundancy, potential, and traits in lake bacterial communities.

Purpose of the Study:

• To assess the influence of stochastic assembly on functional redundancy and trait patterns in parallel bacterial communities.
• To test the hypothesis of "functional dispersal limitation" for cellobiose utilization.
• To explore the links between stochasticity, functional redundancy, and conserved functional patterns.

Main Methods:

• Gene- and genome-resolved metagenomics of 20 parallel lake-water bacterial communities.
• Quantification of functional redundancy across major functional categories.
• Comparison with null models using genomes from the Genome Taxonomy Database (GTDB).

Main Results:

• "Functional dispersal limitation" was rejected as some communities with necessary genes did not utilize cellobiose.
• Functional redundancy mirrored stochastic assembly but was lower within than between communities.
• Category-specific functional dissimilarity patterns were conserved across diversity scales and compared to a large genome database.

Conclusions:

• Stochastic assembly shapes functional trait distribution, with redundancy reflecting overall community traits.
• Functional redundancy and dissimilarity vary by category, indicating conserved functional patterns despite stochastic diversification.
• Null model comparisons reveal varying functional selection strengths and emphasize the interplay of stochasticity, ecological constraints, and habitat in shaping community function.