The evolutionary origin of the universal distribution of mutation fitness effect
Fig 2
Deleterious alleles with higher values of fitness cost, s, are the first to be depleted during the process of adaptation (single run).
(A-E) Evolution of a sample of 102 sequences. Violet dots: better-fit alleles, yellow dots: less-fit alleles. X-axis: the cost in fitness, s, multiplied by 100. The values of s are randomly distributed with the half-Gaussian distribution, s>0, with the average sav = 0.05. Genomic sites are ordered by the value of s. Y-axis: genome number in the sample. The initial population is randomized with the average frequency of deleterious alleles fin = 0.2. Time points in generations are shown. (F) Evolution of the genome distribution in fitness. X-axis: the effective number of deleterious alleles, defined as k = −W/sav. where W is genome fitness. Different colors show discrete time intervals from 0 to 5. The Vertical grey line shows the most-fit class of genomes at t = 0. The emergence of clonal structure in (A-E) coincides with the transition from the selection of pre-existing sequences to the traveling wave regime. The other parameters: population size N = 104, number of sites L = 100, genomic mutation rate μL = 0.05. In the text, we study the ensemble-average allelic frequency averaged over many runs.