Divergence time dating
The divergence time to the most recent common ancestor (TMRCA) ofC. serrulata was estimated to be around 10.6 Mya (PP=1; 95% HPD: 8.83-12.46 Mya), near the middle of Miocene (Figure 7, Table 4). During 10.6 Mya, the northwest group began its divergence from the other groups. When it came to 8.02 Mya, the southwest group and the east group involving the northeast and southest groups, started to separate away.