Unfair trade underground revealed by integrating data with Nash bargaining models

Area of Science:

• Ecology
• Biogeochemistry
• Symbiotic interactions

Background:

• Mutualisms are vital for ecosystem function, involving resource exchange between organisms.
• Potential conflict exists in mutualisms due to differing partner benefits and costs.
• Understanding partner bargaining power is crucial for predicting symbiotic exchange ratios.

Purpose of the Study:

• To investigate bargaining power symmetry in legume-rhizobia nitrogen-fixing symbiosis.
• To determine if plant and bacterial partners have equal or unequal influence on resource exchange.
• To apply economic theory to model symbiotic interactions.

Main Methods:

• Measured carbon and nitrogen dynamics in legume-rhizobia symbiosis.
• Utilized a mathematical modeling framework based on economic principles.
• Tested models of symmetric versus asymmetric bargaining power.

Main Results:

• A model of symmetric bargaining power did not fit the observed data.
• Plant growth benefits significantly influenced trade dynamics more than bacterial benefits.
• Plant bargaining power increased as soil nitrogen availability decreased.

Conclusions:

• Legume-rhizobia symbiosis exhibits asymmetric bargaining power, favoring the plant.
• Plant influence on resource exchange is context-dependent, increasing with lower nitrogen availability.
• Findings emphasize the importance of environmental context in the evolution of mutualism under nutrient enrichment.