FIGURE 3. Intermediate mutators can be fixed during adaptation of finite size populations (10-fold mutators are shown).

From the following article:

Role of mutator alleles in adaptive evolution

F. Taddei, M. Radman, J. Maynard-Smith, B. Toupance, P. H. Gouyon & B. Godelle

Nature 387, 700-702(12 June 1997)


The model is similar to the one described in Fig. 2. Here, however, finite populations were allowed to grow exponentially from 108to 1010individuals and then were diluted back to 108, with random sampling occurring every 7 generations for frequency classes lower than 13 times 10-8 (see Methods for more details about the sampling procedure). Each of 100 independent simulations is represented on these plots. Dotted lines symbolize the populations where the mutator allele has reached over 50%. a, Change in mutator frequency. Mutators can be favoured by hitch-hiking with adaptive mutations and thus become fixed in the population. b, Evolution of the mean fitness of populations subjected to mutation, selection and drift. Fixation of mutator genotypes can accelerate fitness increase.