Growth tradeoffs produce complex microbial communities on a single limiting resource

Area of Science:

• Ecology
• Microbial Ecology
• Theoretical Ecology

Background:

• Understanding community dynamics is fundamental to ecology.
• Higher-order ecological effects beyond pairwise interactions are crucial for complex ecosystems but poorly understood.
• Mechanisms driving these higher-order effects require further investigation.

Purpose of the Study:

• To model microbial growth and competition to elucidate the origins of higher-order ecological effects.
• To investigate how variation in microbial growth traits can generate complex ecological dynamics.
• To explore the implications of these effects for microbial community structure and stability.

Main Methods:

• Mathematical modeling of microbial growth and competition.
• Simulation of microbial populations with varying growth traits (lag times, growth rates) on a single limiting resource.
• Analysis of emergent ecological phenomena such as multistability, neutral coexistence, and competitive exclusion.

Main Results:

• Higher-order ecological effects arise from variation in multiple microbial growth traits, even without direct inter-strain interactions.
• These effects can lead to an unlimited number of strains exhibiting multistability and neutral coexistence, potentially involving keystone strains.
• Observed phenomena include strains coexisting in pairs but not all together, and strains winning pairwise competitions going extinct in mixed cultures.

Conclusions:

• Variation in multiple microbial growth traits is a widespread source of higher-order ecological effects.
• These effects are likely prevalent in microbial populations, particularly in laboratory ecology and evolution experiments.
• The findings offer a new mechanistic understanding of complex ecological dynamics in microbial systems.