Model comparisons.

Comparison of the three models selected by Procedure 2, for each pairwise alignment of 3′ UTRs. MP: mixture proportions; T/T: Transition/Transversion ratio. Class 11 of Dme vs Dsi (MP: 0.7%, Conservation: 56%, GC content: 17% and T/T: 0.5) and the class 9 of Dme vs Dya (MP: 7.5%, Conservation: 85%, GC content: 45% and T/T: 1.1) alignments did not match with other models.