Figure 4

Relevant densities for different target structures. Dependence of $\overline{\rho }$ (black lines) and $\overline{\rho }$ _S (green lines) on the mutation rate μ and the length n of the target structure. The curves correspond to the hairpin structure (solid line), hammerhead structure (dotted line), 3-stem-loop structure (dashed line), model tRNA structure (dotted-dashed line), whose structures are specified in Table 1. The curves for $\overline{\rho }$ almost coincide when the dependent variable is scaled as μn. Population size is N = 602; averages over 4000 generations and 25 realizations have been performed.