Substitution pattern after t₀: (a) relative substitution frequencies determined and presented in the same way as in figure 6a but using only REs with average transversion rates less than 0.02. Note the change in scale for the much larger CpG-based transition (diamonds). (b) The expected stationary GC content computed using the GC-dependent substitution rates shown in (a). Note that it is far from the straight line (the equality of the stationary and regional GC content), indicating that the regional GC content is far from being equilibrated by the current rates. The eventual stationary GC content according to the plot is 35% to 40%