Shimodaira-Hasegawa (SH) test for the topologically unconstrained trees (Figs 1 and 2) and constrained trees (S1 and S2 Figs) in three-gene and four-gene analyses.

Significance was set as alpha = 0.05. The difference in likelihood (ΔlnL) was calculated by subtracting the log likelihood score between the unconstrained and constrained best tree.显著性水平设定为α=0.05。似然差（ΔlnL）通过计算无约束最优树与约束最优树的对数似然值之差得到。