Summary of 8 different models for evolutionary analyses.

Note: The marginal likelihood and tMRCA in the 8 different models were showed in this table. The improvement in marginal likelihood suggested that the GTR substitution model was superior to the HKY model [35]. And the relaxed molecular clock model of uncorrelated lognormal-distributed (UCLD) rate variation among branches fit our data better than strict clock model [34]. The constant (CS) and exponential growth (EG) population size had no significant impact on the analyses. The tMRCA was in units of years before 2009, the 95% HPD was showed in the parentheses.