Fig. 2

Fitness distribution of genotypes obtained from simulation at low and high mutation rates of a population of an ancestral organism (Dark line: resource levels of 10 k and population size of 500; Light lines: all other combinations of these variables, see Additional file 1: Fig. S4). a At low mutation rate, five major peaks (labeled L0–4) are obtained in the distribution. b At a high mutation rate, the distribution becomes more heterogeneous and four major peaks (H0 to H3) are observed. The dotted vertical line for both spectra represents the fitness of the ancestral organism. Y axis represents density (calculated from a kernel density estimate with area under the curve normalized to 1) and X axis represents fitness (defined as the number of births/updates)