A higher-level MRP supertree of placental mammals
1 Division of Biology, Imperial College London, Silwood Park campus, Ascot SL5 7PY, UK
2 Natural History Museum, Cromwell Road, London SW7 5BD, UK
3 School of Biological, Earth and Environmental Sciences, University of New South Wales, NSW 2052, Australia
4 Lehrstuhl für Tierzucht, Technical University of Munich, 85354 Freising-Weihenstephan, Germany
5 Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany
6 Department of Zoology, Box 118525, University of Florida, Gainesville, Florida 32611-8552, USA
BMC Evolutionary Biology 2006, 6:93 doi:10.1186/1471-2148-6-93Published: 13 November 2006
The higher-level phylogeny of placental mammals has long been a phylogenetic Gordian knot, with disagreement about both the precise contents of, and relationships between, the extant orders. A recent MRP supertree that favoured 'outdated' hypotheses (notably, monophyly of both Artiodactyla and Lipotyphla) has been heavily criticised for including low-quality and redundant data. We apply a stringent data selection protocol designed to minimise these problems to a much-expanded data set of morphological, molecular and combined source trees, to produce a supertree that includes every family of extant placental mammals.
The supertree is well-resolved and supports both polyphyly of Lipotyphla and paraphyly of Artiodactyla with respect to Cetacea. The existence of four 'superorders' – Afrotheria, Xenarthra, Laurasiatheria and Euarchontoglires – is also supported. The topology is highly congruent with recent (molecular) phylogenetic analyses of placental mammals, but is considerably more comprehensive, being the first phylogeny to include all 113 extant families without making a priori assumptions of suprafamilial monophyly. Subsidiary analyses reveal that the data selection protocol played a key role in the major changes relative to a previously published higher-level supertree of placentals.
The supertree should provide a useful framework for hypothesis testing in phylogenetic comparative biology, and supports the idea that biogeography has played a crucial role in the evolution of placental mammals. Our results demonstrate the importance of minimising poor and redundant data when constructing supertrees.