Fig. 1

A Map displaying phylogeographic structure within Eutropis multifasciata, with the inset showing the mitochondrial BEAST timetree. Triangular tips in the tree have been collapsed and indicate more than one sample within a clade. The colors of geographic sampling points correspond to the tip colors in the tree and are nested according to the larger colored shapes corresponding to the encircled colored clades in the tree. Subclades are labeled corresponding to the tree tip labels. Nodes in the timetree with posterior probability greater than 0.95 are shown with a black dot, and timescale is in units of million years. Relevant biogeographic features discussed in the text are labeled. The dotted black lines indicate the geographic extent of the major numbered clades. Wallace’s Line and Huxley’s modification are shown in light blue for reference. The underlying map is shaded according to a digital elevation model (SRTM). The sea level bathymetry displays the 40 m (darker grey) and 120 m (lighter grey) depth contours (GEBCO), and indicate the areas exposed during periods of reduced sea levels. Location of inset maps shown by boxes. B Inset map of Sulawesi. White-rimmed points within the green T3 clade display additional phylogenetic substructure not indicated on the collapsed timetree. C Inset map of Taiwan, Ludao, and Lanyu