The original Fig. 2 in this paper contains a single inconsequential typo in each of the RRR, YRR, and YRY cubes. Specifically, the vertex labeled GCA in the RRR cube should read AAA, the vertex labeled GCA in the YRR cube should read CGA, and the vertex labeled GCA in the YRY cube should read CAT. These typos had no impact on our analyses. For clarity, Fig. 2 is reproduced below with these typos corrected.
![](https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20201208150827206-0673:S0033583520000116:S0033583520000116_fig2.png?pub-status=live)
Fig. 2. The hypercube of all eight cube octet sequence classes (shown in red) located at each apex of the hypercube, illustrating the interconnectedness of the cycles associated with the full cascade of codon interconversions via sequential site changes. Transition mutations occur within a cube, while transversion mutations link one cube to another.