The evolution of South American endemic canids: a history of rapid diversification and morphological parallelism

The origin of endemic South American canid fauna has been traditionally linked with the rise of the Isthmus of Panama, suggesting that diversification of the dog fauna on this continent occurred very rapidly. Nevertheless, despite its obvious biogeographic appeal, the tempo of Canid evolution in South America has never been studied thoroughly. This issue can be suitably tackled with the inference of a molecular timescale. In this study, using a relaxed molecular clock method, we estimated that the most recent common ancestor of South American canids lived around 4 Ma, whereas all other splits within the clade occurred after the rise of the Panamanian land bridge. We suggest that the early diversification of the ancestors of the two main lineages of South American canids may have occurred in North America, before the Great American Interchange. Moreover, a concatenated morphological and molecular analysis put some extinct canid species well within the South American radiation, and shows that the dental adaptations to hypercarnivory evolved only once in the South American clade.