Biogeography and early emergence of the genusDidelphis(Didelphimorphia, Mammalia)

Abstract

AbstractThe genusDidelphiscomprises six species of relatively large‐sized New World marsupials ranging from Argentina to Canada. Most of the diversity of the genus occurs in the Neotropical region, where two groups of species are currently recognized: theDidelphis marsupialisgroup, includingD. marsupialisandD. aurita,and theD. albiventrisgroup comprisingD. albiventris,D. imperfectaandD. pernigra. The genus also includesD. virginiana,the only livingDidelphisspecies reaching the Nearctic region.Didelphis'wide latitudinal distribution, wide range of environments in which it can be found as well as the disjunct, and spatially complementary distributions shown by its species raise some questions regarding the historical biogeography of the genus and how it relates to the geological and climatic events of the Plio‐Pleistocene. The present study is aimed at answering biogeographic and historical questions concerning the evolution ofDidelphis.We employed molecular methods to infer a multi‐locus time‐calibrated phylogeny including allDidelphisspecies which served as a framework for biogeographic analyses. Our results suggest that the basalmost divergence inDidelphisis an event older than previously thought, probably having taken place at some point betweenca.4.3 and 7.4 Mya following a vicariant event. Our results also suggest a northern South American origin for the genus, and that it possibly expanded its range to North America before the GABI. Climatic‐driven modifications in Neotropical environments during the late Pliocene and early Pleistocene favored the dispersion to new ecosystems triggering the emergence of new lineages.