Fitness variation in isogenic populations leads to a novel evolutionary mechanism for crossing fitness valleys

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Authors Debra Van Egeren, Thomas Stenskrog Madsen, Franziska Michor
Journal/Conference Name Communications Biology
Paper Category ,
Paper Abstract Individuals in a population often have different fitnesses even when they have identical genotypes, but the effect of this variation on the evolution of a population through complicated fitness landscapes is unknown. Here, we investigate how populations with non-genetic fitness variation cross fitness valleys, common barriers to adaptation in rugged fitness landscapes in which a population must pass through a deleterious intermediate to arrive at a final advantageous stage. We develop a stochastic computational model describing the dynamics of an asexually reproducing population crossing a fitness valley, in which individuals of the same evolutionary stage can have variable fitnesses. We find that fitness variation that persists over multiple generations increases the rate of valley crossing through a novel evolutionary mechanism different from previously characterized mechanisms such as stochastic tunneling. By reducing the strength of selection against deleterious intermediates, persistent fitness variation allows for faster adaptation through rugged fitness landscapes.Debra Van Egeren et al. present a stochastic computational model of the dynamics of an asexually reproducing population, such as somatic or cancer cells, crossing a fitness valley. They find that fitness variation persisting across generations promotes weaker selection against deleterious intermediates, thereby increasing the rate of valley crossing.
Date of publication 2018
Code Programming Language Python
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