Adaptive diversification of a plastic trait in a predictably fluctuating environment

Area of Science:

• Evolutionary biology
• Microbial ecology

Background:

• Phenotypic plasticity is often reduced in stable, isolated environments, driving evolutionary diversification.
• The role of plasticity in sympatric diversification (without geographic isolation) remains less understood.

Purpose of the Study:

• To investigate the role of phenotypic plasticity in sympatric diversification.
• To model the ecological and evolutionary dynamics of Escherichia coli in batch cultures to understand diversification mechanisms.

Main Methods:

• Ecological and evolutionary modeling of Escherichia coli.
• Simulation of bacterial populations in batch cultures with fluctuating environments.

Main Results:

• Identified an evolutionary pathway for metabolic diversification in sympatric conditions without spatial structure.
• Demonstrated that evolutionary branching can lead to stable coexistence of generalist and specialist ecotypes in predictably fluctuating environments.
• Diversification and coexistence are favored by steep reaction norms and convex trade-offs between metabolic pathways.

Conclusions:

• Diversification due to reduced phenotypic plasticity can occur in sympatric settings.
• This process does not require allopatric isolation, reduced environmental variability, or an explicit cost of plasticity.