Year: 2016
Type: article
Abstract: Placental mammals comprise three principal clades: Afrotheria (e.g., elephants and tenrecs), Xenarthra (e.g., armadillos and sloths), and Boreoeutheria (all other placental mammals), the relationships among which are the subject of controversy and a touchstone for debate on the limits of phylogenetic inference. Previous analyses have found support for all three hypotheses, leading some to conclude that this phylogenetic problem might be impossible to resolve due to the compounded effects of incomplete lineage sorting (ILS) and a rapid radiation. Here we show, using a genome scale nucleotide data set, microRNAs, and the reanalysis of the three largest previously published amino acid data sets, that the root of Placentalia lies between Atlantogenata and Boreoeutheria. Although we found evidence for ILS in early placental evolution, we are able to reject previous conclusions that the placental root is a hard polytomy that cannot be resolved. Reanalyses of previous data sets recover Atlantogenata + Boreoeutheria and show that contradictory results are a consequence of poorly fitting evolutionary models; instead, when the evolutionary process is better-modeled, all data sets converge on Atlantogenata. Our Bayesian molecular clock analysis estimates that marsupials diverged from placentals 157-170 Ma, crown Placentalia diverged 86-100 Ma, and crown Atlantogenata diverged 84-97 Ma. Our results are compatible with placental diversification being driven by dispersal rather than vicariance mechanisms, postdating early phases in the protracted opening of the Atlantic Ocean.
Source: Genome Biology and Evolution
DOI: 10.1093/gbe/evv261
Institutions: National University of Ireland, Maynooth, University of Bristol, Queen Mary University of London, University College London, University of California San Diego, The University of Texas at Austin, University of Leeds, Mount Desert Island Biological Laboratory, University of Cambridge, University of Illinois Urbana-Champaign, Dartmouth College
Language: English
Subfield: Paleontology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,850
Awards: Collaborative Research: Novel Methodologies for Genome-scale Evolutionary Analysis of Multi-locus data, Bayesian Estimation of Species Divergence Times Integrating Both Fossil and Molecular Information, Comparative Biology of Tissue Repair, Regeneration and Aging, G316767904, Bristol-2013-DTG Funding 13 Studentships, Representation and Incorporation of Fossil Data in Molecular Dating of Species Divergences, Bayesian Estimation of Species Divergence Times Integrating Fossil and Molecular Information, G6201322808, The Maine Biomedical Research Network (INBRE)
OpenAlex ID: W2231539885