Analysis of the Fitness Effect of Compensatory Mutations

Zhang, Liqing and Watson, Layne T. (2008) Analysis of the Fitness Effect of Compensatory Mutations. Technical Report TR-08-01, Computer Science, Virginia Tech.

Abstract

We extend our previous work on the fitness effect of the fixation of deleterious mutations on a population by incorporating the effect of compensatory mutations. Compensatory mutations are important in the sense that they make the deleterious mutations less deleterious, thus reducing the genetic load of the population. The essential phenomenon underlying compensatory mutations is the nonindependence of mutations in biological systems. Therefore, it is an important phenomenon that cannot be ignored when considering the fixation and fitness effect of deleterious mutations. Since having compensatory mutations essentially changes the distributional shapes of deleterious mutations, we can consider the effect of compensatory mutations by comparing two distributions where one distribution reflects the reduced fitness effects of deleterious mutations with the influence of compensatory mutations. We compare different distributions of deleterious mutations without compensatory mutations to those with compensatory mutations, and study the effect of population sizes, the shape of the distribution, and the mutation rates of the population on the total fitness reduction of the population.