Figure 1.

Examples of a common situation (“phylogeographic category I”; ref. 6) in which two distinctive, geographically oriented mtDNA phylogroups have been reported within a vertebrate species. Shown are cluster phenograms for the bottlenose dolphin (Tursiops truncatus; patterned after data presented in ref. 37), the Canada goose (Branta canadensis; patterned after data presented in ref. 38), the musk turtle (Sternotherus minor; patterned after data presented in refs. 39 and 40), the killifish (Fundulus heteroclitus; patterned after data presented in ref. 41), and the walleye fish (Stizostedion vitreum; patterned after data presented in ref. 42; see also ref. 44 for a recent update).