Rapid evolution destabilizes species interactions in a fluctuating environment.

Area of Science:

• Ecology
• Evolutionary Biology
• Microbiology

Background:

• Positive species interactions are fundamental to ecosystem function.
• Understanding the stability of these interactions under varying environmental conditions is crucial.
• Evolutionary timescales and environmental fluctuations, including competition, impact interaction stability.

Purpose of the Study:

• To investigate the stability of a two-species microbial interaction over 200 generations.
• To compare the effects of constant versus fluctuating environments on species coexistence.
• To determine the role of rapid evolution and genetic adaptation in interaction stability.

Main Methods:

• Utilized a two-species microbial system with nutrient-modulated interactions.
• Evolved replicate populations in parallel in constant and fluctuating (commensalism-competition) environments.
• Sequenced full genomes of isolated clones at various time points to identify genetic adaptations.

Main Results:

• Species stably coexisted in the constant commensal environment.
• In the fluctuating environment, species extinction occurred in 50% of replicates.
• Extinction events were deterministic and reproducible, driven by adaptive mutations in specific genes.

Conclusions:

• Long-term stability of positive pairwise interactions is compromised in fluctuating environments.
• Rapid evolution, driven by specific genetic adaptations, can destabilize ecological communities.
• Environmental instability poses a significant challenge to the persistence of mutually beneficial species interactions.