Segmentation characteristics of models selected by Procedure 2.

Length: number of alignment columns in the component; Nfixed: number of fixed change-points, corresponding to the boundaries of alignment blocks; k: posterior average number of change-points; L: posterior average length of segments. Note the length of the coding sequence is equal to that of the 3′ UTRs for the same species pair, once the number of fixed change-points (corresponding to the ends of alignment blocks) is added to the length.