Figure 7
(A) Model 1. (B) Model 2. (C) Model 3. (D) Model 4. Introns are not lost randomly. The four models are described in Table 3. However, as Models 2 and 4 assume that cpb-2 intron #2 was created sometime after the split between the ancestor of C. japonica and that of the other species, this intron was excluded from the calculations, leaving only 33 ancestral introns in the data set for these two models. This correction allowed us to consider only introns that have existed for the same length of time.
