Figure 4. Models used to test Pleistocene refugial hypotheses.

(a) Single refugium hypothesis: populations from eastern, northwestern, and central Yunnan Plateau are derived from a single refugium and began to expand at the end of the last glacial maximum (c. 18 000 years BP). (b) Multiple refugia hypothesis: two lineages split at the Middle Pleistocene (T = 640 000 years BP), with the northwestern plus central branch diverged into two clades at 360 000 years ago (T3+T4). T1 (200 000 years BP), T2 (110 000 years BP), and T3 (100 000 years BP) were derived from the estimates of TMRCA.