From the Old World to the New World: A molecular chronicle of the phylogeny and biogeography of hystricognath rodents

Hystricognath rodents include Old World Phiomorpha and New World Caviomorpha. These two groups have an enigmatic biogeographical history. Using a nuclear marker, the exon 28 of the von Willebrand Factor gene (vWF), we reconstructed the phylogenetic relationships among 23 Hystricognathi species. These taxa encompass the complete familial diversity of the Hystricognathi. Our results indicate a basal trifurcation of hystricognaths leading to Hystricidae, Phiomorpha s.s. (Bathyergidae, Thryonomyidae, and Petromuridae), and Caviomorpha. The monophyly of caviomorphs is robustly supported, confirming a single colonization event of South America by hystricognaths. Caviomorpha are divided into four lineages: Cavioidea, Erethizontoidea, Chinchilloidea, and Octodontoidea. Furthermore, we suggest that (1) Chinchillidae and Dinomyidae are sister clades, (2) Abrocomidae is a true Octodontoidea, and (3) Capromyidae, Echimyidae, and Myocastoridae cluster together. Surprisingly, Erethizontidae does not appear to be the most diverged caviomorph lineage. The molecular results are discussed in the light of previous paleontological and morphological observations. Local molecular clocks are used to estimate divergence dates among hystricognath lineages. An Asian origin is suggested for Caviomorpha, and a colonization route through Australia and Antarctica is indicated as an alternative to the hypothesis of a transatlantic migration of Caviomorpha from Africa to South America.