Departamento de Genética, IB, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
J Evol Biol. 2010 Feb;23(2):311-22. doi: 10.1111/j.1420-9101.2009.01901.x. Epub 2009 Nov 26.
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.
南美的地方性犬科动物群的起源传统上与巴拿马地峡的隆起有关，这表明该大陆的犬科动物多样性迅速多样化。然而，尽管它具有明显的生物地理吸引力，但南美的犬科动物进化速度从未得到过彻底研究。这个问题可以通过推断分子时间尺度来解决。在这项研究中，我们使用了一种放松的分子钟方法，估计南美的犬科动物最近的共同祖先生活在大约 400 万年前，而该分支内的所有其他分支都发生在巴拿马地峡隆起之后。我们认为，南美的两个主要犬科动物分支的祖先的早期多样化可能发生在北美，即在“大置换”之前。此外，形态学和分子分析的综合分析表明，一些已灭绝的犬科动物物种很好地处于南美的辐射范围内，并且表明对超肉食性的牙齿适应仅在南美的分支中进化了一次。
