The biogeography of Dromiciops in southern South America: Middle Miocene transgressions, speciation and associations with Nothofagus

• DOI: 10.1016/j.ympev.2021.107234
• Publication Date: 2021-06-17T11:45:13Z
• Authors: Julian F. Quinter...; Pablo Saenz-Agudelo; Juan L. Celis-Diez; Guillermo C. Amico; Soledad Vazquez; Aaron B.A. Shafer; Roberto F. Nespolo
• Keywords: 0106 biological sciences; 570; Microbiotheria; 550; Dromiciops bozinovici; DNA, Mitochondrial; 01 natural sciences; PHYLOGEOGRAPHY; 03 medical and health sciences; Dromiciops gliroides; DROMICIOPS GLIROIDES; https://purl.org/becyt/ford/1.6; Animals; Chile; Middle Miocene Transgression; https://purl.org/becyt/ford/1; Ecosystem; Phylogeny; 0303 health sciences; 15 Vida de ecosistemas terrestres; MICROBIOTHERIA; 15 Life on Land; 15. Life on land; Phylogeography; Marsupialia; DROMICIOPS BOZINOVICI; Nothofagus; MIDDLE MIOCENE TRANSGRESSION; NOTHOFAGUS

AbstractAimSeveral geological events affecting Southern South America during the middle Miocene climatic optimum acted as important drivers of diversification to the biota. This is the case of Microbiotheria, for whichDromiciopsis considered the sole surviving lineage, the sister group of Eomarsupialia (Australian marsupials). Three mainDromiciopsgenetic lineages are known, whose divergence was initially attributed to recent Pleistocene glaciations. Using fossil-calibrated dating on nuclear and mitochondrial genes, here we reevaluate this hypothesis and report an older (Miocenic) biogeographic history for the genus.LocationSouthern South America.MethodsPhylogenetic reconstruction using sequences from two mitochondrial DNA and four nuclear DNA genes in 159 specimens, from 31 sites across Chile and Argentina. Divergence time estimation using fossil calibration.ResultsOur phylogenetic analysis resolved four well supported clades with discrete geographic distributions. The oldest and most differentiated clade corresponds to that of the northern distribution (35.2°S to 39.3°S), which would be a different species (D. bozinovici, sensu D’elia et al. 2016). According to our estimations, this species shared a common ancestor withD. gliroides(southern clades) about 13 million years ago (95% CI: 6.4-25.3). The southern clades (39.6°S to 42.0°S), showed a divergence time ranging from 9.57 to 6.5 Mya. Strong genetic structure was detected from north to south but not across the Andes, or between Chiloé island/ mainland. Demographic equilibrium is inferred to the northern clade, and recent demographic expansions was detected in the central and southern clades.Main conclusionsThe whole diversification ofDromiciopsoccurred within the Miocene, being the Middle Miocene transgression (MMT), the massive marine flooding that covered several lowlands of the western face of los Andes between 38-48° S, the most likely diversifying force. This was the result of an increase in global sea levels due to the Miocene climatic optimum, which shaped the biogeographic origin of several species, includingNothofagusforests, the habitat main ofDromiciops.