Figure 3.

Histograms of estimated substitution rate differences between annual-like and perennial-like species pairs in 1000 independent replicates that were simulated under the average nucleotide substitution parameter sets estimated from actual ITS sequences (see Table 2). The value axis gives the ratio of the faster substitution rate over the slower substitution rate. The rate difference ratio was assigned a negative value when the perennial-like taxon had a faster estimated substitution rate and was positive when the annual-like taxon had a faster estimated substitution rate.