BEAST tree reconstructed with the BioGeoBEARS results. Colors on the nodes and beside the tips denote inferred ancestral areas and current distributions, respectively. Geographic regions, marked using different colors, are depicted on the map A). Summarized BioGeoBEARS results B). Pie charts on the nodes indicate the percentages of ancestral area reconstructions C). Different periods are highlighted using different colors: light blue (35 to 90 million years ago [Mya]) indicates the period when land bridges connected Asia and North America as well as Western Eurasia and North America, while Western Eurasia and East Asia were separated by the Turgai Strait, which closed 30 Mya (Sanmartín et al. 2001). Dark gray (30 to 35 Mya) indicates the period when Western Eurasia and East Asia were disconnected but the Bering Land Bridge connected Asia and North America, although most dispersal events had ceased (Sanmartín et al. 2001). Light gray (30 to 20 Mya) indicates the period when Western Eurasia and East Asia became connected after the closure of the Turgai Strait and the Bering Land Bridge was available, although dispersal between Asia and North America was rare. Light yellow (0 to 1.5 and 3.5 to 20 Mya) indicates the period when the Bering Land Bridge was available, facilitating biotic exchange between Asia and North America, but no land bridge existed 1.5 to 3.5 Mya.