Fig. 6.

Mosaic and concerted evolution when brain size has upper and lower limits. a–c Evolution of ‘mosaicism’ under alternative conditions. a–c Each plot depicts the ‘degree of mosaicism’ (y-axis, defined as the natural log of the ratio between the largest brain component and the smallest brain component in each individual, averaged across the population) as a function of developmental coupling D (x-axis) under different environments, defined by their functional coupling F, with an average benefit to cost ratio (B̅/C) of 1.5 and a mutation step size of 5%. d, e Summary of the effects of varying F and D, and F and B̅/C, respectively, on the degree of mosaicism. f–h Selected examples of competition between evolving populations with different D values. Each plot depicts the frequency of that D value relative to the total population (y-axis) as a function of developmental coupling D (x-axis) under alternative environments defined by their functional coupling F, with a benefit to cost ratio (B̅/C) of 1.5 Each data point is the outcome of one simulation run and the black bar indicates the mean of these runs. For comparison, grey bars show the means from the same unbounded simulations in Fig. 2a–c. i–k Each plot depicts the average relative frequencies of D = 0 (yellow) and D = 1 (green) at three B̅/C ratios, across three F values representing low (d), moderate (e) and high (f) functional coupling. For comparison, results from the same unbounded simulations in Fig. 3d, e are shown in faded colours. See Additional file 1: Figure S20-S23 for further full results varying B̅/C and F