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

Optimization of AC/CA-mediated CBCs on ITS2 gene trees for four lineages. AC-mediated CBCs are inferred in (A) lineage Aralia and (B) lineage Astilbe; CA-mediated CBCs are inferred in (C) lineage Meconopsis and (D) lineage Celastrus. Base-pair states involved in CBCs are indicated using different colors for the applicable branches and species. Species names in bold font indicate the outgroup, which was used to root each tree. Branches with ≥0.5 posterior probabilities for Bayesian inference are highlighted in bold. Numbers following a species name indicate GenBank accession numbers.