Concurrent ecological and evolutionary processes contribute to mutualism breakdown between legumes and rhizobia.

Ecological and evolutionary processes jointly cause a 50% decline in host benefit in legume-rhizobium mutualism after 33 years of nitrogen fertilization.

• Why it matters: Understanding how short-term ecological and evolutionary changes impact mutualisms is crucial for predicting responses to environmental disturbances, especially in microbial communities.
• What they did: Researchers combined inoculation experiments, 16S rRNA gene sequencing, and structural equation modeling to analyze changes across bacterial community levels, focusing on symbiosis plasmids and Rhizobium diversity.
• The result: The study found that ecological shifts toward rarer, less beneficial symbionts and evolutionary degradation of symbiont quality both contributed equally to mutualism breakdown, highlighting the intertwined roles of ecology and evolution.