Adenine·cytosine substitutions are an alternative pathway of compensatory mutation in angiosperm ITS2

A schematic representation of substitution processes involving compensatory mutations. The base-pair substitutions in black are existing pathways proposed by Tillier and Collins (1998); the base-pair substitutions in red are proposed in this study. The thickness of the solid arrows and their shading indicate the substitution rates inferred from our data sets. The dashed arrows indicate the simultaneous double-substitution pathway that was not supported by our best-fit 16D/E/F/J model for 70 of the 80 lineages. Letter(s) on the arrows represent substitution rates between base pairs.