Trade-off between reciprocal mutualists: local resource availability-oriented interaction in fig/fig wasp mutualism

Area of Science:

• Evolutionary Biology
• Mutualism Studies
• Ecology

Background:

• Mechanisms preventing conflict in cooperative systems are a major evolutionary biology problem.
• Previous hypotheses include self-restraint, dispersal, and spatial constraints to maintain cooperation.
• The obligate fig-fig wasp mutualism serves as a model to test these hypotheses.

Purpose of the Study:

• To investigate if self-restraint, dispersal, and spatial constraints sufficiently maintain stable cooperation between figs and fig wasps.
• To determine the conditions under which cooperation or conflict occurs in the fig-fig wasp mutualism.
• To identify key factors crucial for the maintenance and evolution of cooperation in this system.

Main Methods:

• Observational study of obligate cooperation between *Ficus racemosa* and *Ceratoslen fusciceps*.
• Correlation analysis of fig seed viability with pollinator offspring (galls) under varying flower availability and foundress numbers.
• Experimental manipulation of foundress numbers to assess resource competition dynamics.

Main Results:

• Fig seed viability positively correlates with wasp offspring when vacant female flowers are abundant and foundress numbers are low.
• A negative correlation emerges when vacant female flowers are scarce and foundress numbers increase.
• The interaction is conditional: cooperation prevails with plentiful resources, while conflict arises when resources are limited.

Conclusions:

• Existing hypotheses (self-restraint, dispersal, spatial heterogeneity) are insufficient to prevent symbiont over-exploitation of resources.
• Conflict arises when local resources become saturated with symbionts, disrupting cooperation.
• Repressing symbiont proliferation during resource limitation is vital for maintaining and evolving mutualistic cooperation.