Speeding up evolutionary search by small fitness fluctuations

TL;DR

This paper demonstrates that small, time-varying fluctuations in fitness landscapes can significantly accelerate evolutionary search by enabling populations to escape local minima more effectively.

Contribution

It introduces a model showing how minor fitness fluctuations induce high effective diffusion, speeding up evolution in populations.

Findings

Small fitness fluctuations increase population diffusion.

Time-dependent fitness variations help escape local minima.

The effect is robust across various models.

Abstract

We consider a fixed size population that undergoes an evolutionary adaptation in the weak mutuation rate limit, which we model as a biased Langevin process in the genotype space. We show analytically and numerically that, if the fitness landscape has a small highly epistatic (rough) and time-varying component, then the population genotype exhibits a high effective diffusion in the genotype space and is able to escape local fitness minima with a large probability. We argue that our principal finding that even very small time-dependent fluctuations of fitness can substantially speed up evolution is valid for a wide class of models.