A mechanistic framework of enemy release.

Area of Science:

• Ecology
• Evolutionary Biology
• Invasion Biology

Background:

• The enemy release hypothesis (ERH) is a leading explanation for the success of exotic species.
• Current ERH research often lacks explicit links between enemy release evidence and exotic species performance, creating uncertainty.
• This gap hinders a comprehensive understanding of enemy release's role in biological invasions.

Purpose of the Study:

• To demonstrate that enemy release effects on exotic species performance result from the interplay of three key factors: enemy impact, enemy diversity, and host adaptation.
• To identify seven ecological contexts that modulate these factors.
• To propose a mechanistic factor-context framework for the ERH to enhance predictive capacity and guide management.

Main Methods:

• The study synthesizes existing research and re-analyzes a meta-analysis to illustrate the importance of ecological contexts.
• A factor-context framework is developed to structure the ERH.
• The framework integrates enemy impact, diversity, and host adaptation with contextual factors like time since introduction and resource availability.

Main Results:

• Enemy release effects are contingent upon the interaction of enemy impact, diversity, and host adaptation.
• Seven ecological contexts significantly modulate these interactions, influencing exotic species performance.
• Inconsistent findings in ERH studies often stem from neglecting these crucial ecological contexts.

Conclusions:

• A refined ERH framework, incorporating factors and contexts, offers more generalizable predictions for exotic species success.
• This approach unifies various enemy-related invasion hypotheses.
• The factor-context framework provides a clear roadmap for future research and effective management strategies for biological invasions.