Figure 7

Standardized substitution rates across the mitochondrial genome for selected branches or clusters. For each 1000 bp window applied to a set of branches, standardized substitution rates were obtained by first dividing by the median window value for that branch, and then subtracting this value from the average across all non-snake branches. This helps to visualize regions of the genome that are evolving at slower or faster rates, with the average tetrapod relative rate being zero. Branches or branch sets shown are (A) the branch leading to the most recent common ancestor of all snakes and of the Alethinophidia; (B) the branch leading to the most recent common ancestor of the Colubroidea and the sum of all colubroid terminal branches; and (C) the branch leading to the most recent common ancestor of the Acro-Heno clade and the sum of all Acro-Heno clade terminal branches.