Colonization-persistence trade-offs in natural bacterial communities

Area of Science:

• Community Ecology
• Microbial Ecology
• Theoretical Ecology

Background:

• Fitness equalizing mechanisms, such as trade-offs, are crucial for species coexistence in community ecology.
• These mechanisms are understudied in highly diverse microbial communities, where coexistence is often attributed to niche differentiation and high dispersal.
• The principle 'everything is everywhere, but the environment selects' often guides microbial community dynamics.

Purpose of the Study:

• To investigate the role of fitness equalizing mechanisms in promoting species coexistence within bacterial communities.
• To analytically derive colonization-persistence trade-offs under fitness equalization assumptions.
• To identify signals of these trade-offs in natural bacterial communities and determine which species subsets drive them.

Main Methods:

• Utilized a dynamical stochastic model grounded in island biogeography theory.
• Analyzed temporal dynamics of bacterial communities across three distinct systems: soils, alpine lakes, and shallow saline lakes.
• Assumed fitness equalization mechanisms to derive and test for colonization-persistence trade-offs.

Main Results:

• Successfully derived colonization-persistence trade-offs analytically under fitness equalization.
• Detected evidence of these trade-offs in natural bacterial communities across the studied systems.
• Demonstrated that rare taxa drive the trade-off in aquatic communities (alpine lakes, saline lakes), while core taxa drive it in soil communities.

Conclusions:

• Equalizing mechanisms, particularly colonization-persistence trade-offs, play a more significant role in bacterial community dynamics than previously recognized.
• Different species subsets (rare vs. core) are responsible for driving these trade-offs in distinct environmental contexts.
• Dynamical models are essential for understanding temporal patterns and processes in highly diverse microbial communities.