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Comparison of lineage-specific evolutionary rates. The graph is a plot of the 54 root-to-tip distances calculated from branch lengths estimated under the GTR+Γ8 model on the reference topology (see Figure 5) for the concatenations of rRNA-coding (y-axis) and protein-coding (x-axis) mitochondrial genes. Symbols corresponding to non-bilaterian outgroups (green squares), tunicates (red triangles), and all other bilaterians (blue diamonds) are indicated. The phylograms showing the branch lengths inferred from each dataset are presented with the highly evolving tunicates figured in red. The linear regression dotted line is figured with its associated equation and correlation coefficient. The y = x line is also indicated to underline the difference in average evolutionary rate between the rRNA and protein mitochondrial partitions.