Within clade II, one dispersal event from Japan to Taiwan occurred in the Early Pleistocene (ca. 1.34 Ma; 95% HPD: 0.69–2.18; node 5). The eustatic sea-level fluctuation during this period, as well as global cooling (Fig. 2), may have triggered Coptis range expansion from Japan to Taiwan via the Ryukyu Islands, and may have subsequently caused range fragmentation. A similar scenario also explains the current distribution of Taiwanese Chamaecyparis formosensis Matsum. and C. taiwanensis Masam. & Suzuki (Cupressaceae) from hypothetical Japanese ancestors . Our analysis on Dichocarpum W.T. Wang & P.G. Xiao indicates that Taiwanese D. arisanense (Hayata) W.T. Wang & P.G. Xiao could have originated from mainland China in the Early Pleistocene (ca. 1.26 Ma, 95% HPD: 0.48–2.33) . These studies support the hypothesis that temperate elements of the flora of Taiwan recently migrated from mainland China and Japan .