Figure 2.

Branch lengths associated with the myoglobin and myosin alignments. Red line indicates the median value, and the top and bottom of the box indicate the upper and lower quartile values, respectively. Whiskers represent the largest and smallest values within 1.5 × IQR (inter-quartile range), and pluses represent outliers, or points outside of 1.5 × IQR. The distribution of branch lengths in the myosin tree is clearly wider and more variable than the distribution of branch lengths in the myoglobin tree.