Epigenetic switching as a strategy for quick adaptation while attenuating biochemical noise

Area of Science:

• Evolutionary biology
• Systems biology
• Biophysics

Background:

• Epigenetic switches are bistable molecular systems capable of switching between heritable phenotypes without DNA mutation.
• Their evolutionary origins as a bet-hedging mechanism and conditions for outcompeting genetic mutation remain unclear.

Purpose of the Study:

• To investigate the evolutionary trajectories and conditions under which epigenetic switches can outperform genetic adaptation.
• To model a system capable of both genetic adaptation and epigenetic switching.

Main Methods:

• Computer simulations of a mechanistic, biophysical model of a self-activating genetic circuit.
• Evolution of genetic circuits in a fluctuating environment with alternating selection for low and high protein expression.
• Analysis of trade-offs between adaptation speed and phenotypic robustness to noise.

Main Results:

• Populations first adapted genetically to facilitate faster future adaptation.
• Epigenetic switching emerged and competed with genetic adaptation, showing superiority in fast-fluctuating environments.
• Genetic adaptation was favored in slow-fluctuating environments for maximal robustness.

Conclusions:

• A trade-off exists between minimizing adaptation time and maximizing robustness to biochemical noise.
• Epigenetic switching is advantageous in rapidly changing environments due to faster adaptation and noise attenuation.
• This study elucidates conditions favoring epigenetic over genetic adaptation, offering insights into bet-hedging strategies.