Figure 3. Relation between mutation rates, genome size and fitness.

(a) Mutation rates, genome size and fitness of the last common ancestors for the different mutation rates and the two target sets. For each mutation rate four repetitions of a simulation (circles and stars) with a different seed and the average, are shown. Except for target set 1 under , the decrease in genome size does not lead to a comparable decrease in fitness. (b) Number of sequences (above) and the functional structures encoded (below), for both target sets under the different mutation rates. Blue bars are the total number of sequences and structures. Yellow bars depict the number of sequences coding for adapters (above) and functional structures guided by adapters (below). While under low to moderate mutation rates almost all functional structures are acquired without the need for RNA-adapters, under high mutation rates, they are commonly incorporated into the coding structure of protocells. This transition explains the relation between mutation rates, genome size and fitness, observed in (a).