Evolution induced state shifts in a long-term microbial community experiment.

Area of Science:

• Ecology and evolutionary biology
• Microbial ecology
• Systems biology

Background:

• Biological communities are complex and dynamic, with poorly understood long-term behavior and predictability.
• Eco-evolutionary feedback, where Darwinian evolution shapes ecosystems, is a key challenge in ecology.
• Previous studies on simplified microbial systems offer insights, but multispecies community dynamics driven by intraspecific selection are less understood.

Purpose of the Study:

• To investigate how species evolution impacts multispecies community states.
• To quantify temporal changes in species abundance and individual genome evolution within a synthetic bacterial community.
• To demonstrate eco-evolutionary feedbacks in a complex community over extended timescales.

Main Methods:

• Conducted a four-year evolution experiment with a 23-species synthetic bacterial community.
• Propagated communities in two environments: control medium and medium with streptomycin.
• Analyzed community composition and genome evolution to track species abundances and adaptive mutations.

Main Results:

• Community dynamics were environment-dependent and reproducible across replicates.
• The evolution of streptomycin resistance in a single species induced abrupt community state shifts.
• Detected adaptive mutations and community state shifts occurring over long evolutionary timescales.

Conclusions:

• Provides direct evidence of eco-evolutionary feedbacks in a multispecies community.
• Demonstrates how a single adaptive mutation can reorganize complex ecological networks.
• Highlights the environment-specific and reproducible nature of community dynamics and evolution.