Effects of multiple dimensions of bacterial diversity on functioning, stability and multifunctionality

Area of Science:

• Microbial ecology
• Ecosystem functioning
• Biodiversity research

Background:

• Bacteria are crucial for ecosystem services, yet factors influencing their functioning remain poorly understood.
• While biodiversity impacts macrobiotic communities, its effect on bacterial communities is less clear, often attributed to functional redundancy.
• The concept of high functional redundancy in bacterial communities has been questioned.

Purpose of the Study:

• To investigate the impact of bacterial diversity changes on ecosystem functioning.
• To assess how different diversity metrics (species, phylogenetic, functional) affect bacterial abundance, stability, nitrogen concentration, and multifunctionality.
• To evaluate the generality of findings through a literature review of dilution-to-extinction experiments.

Main Methods:

• Conducted an outdoor dilution-to-extinction experiment with four lake bacterial communities.
• Manipulated bacterial diversity, creating a richness gradient from 15 to 280 operational taxonomic units (OTUs).
• Analyzed relationships between diversity metrics and ecosystem functions, supplemented by a literature review of 24 studies.

Main Results:

• Observed varied relationships between diversity and functioning, ranging from negative to positive, dependent on the specific lake, diversity dimension, and function.
• A consistent positive relationship was found only between phylogenetic diversity and bacterial abundance across all lakes.
• A literature review confirmed that approximately 25% of studies found positive diversity-functioning relationships.

Conclusions:

• Bacterial community functioning demonstrates relative resistance to reductions in diversity.
• The assumption of universal high functional redundancy may not fully explain the observed diversity-functioning relationships.
• Further research is needed to fully elucidate the complex interplay between bacterial diversity and ecosystem processes.