Figure 6

Occurrence/frequency of substitutions of ITS2 base pairs, and homoplasious changes, mapped upon ITS2 helices. Occurrence and frequency of all compensatory (i.e. CBCs, hCBCs) and non-compensatory substitutions of ITS2 base pairs, and homoplasious changes (parallelisms, convergences, reversals), mapped upon ITS2 helices. Eight invariant base pairs are in bold; the conserved parts of helices 2 and 3 are in gray. Base pairs displaying CBCs + hCBCs are indicated in pink, pairs evolved exclusively via CBCs are in blue, and pairs developed solely via hCBCs are drawn in red. Non-compensating substitutions (N-N ⇔ N×N) were especially frequent in homoplasious positions of Helix 1 and in two pairs of Helix 3 (55/120, 62/114). For Helix 1 and 3 base pairs, the total number of non-compensatory changes cannot be estimated precisely due to their high substitution frequency.