MBE Advance Access published online on September 19, 2007
Molecular Biology and Evolution, doi:10.1093/molbev/msm201
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Research article |
Retroposed Elements and their Flanking Regions Resolve the Evolutionary History of Xenarthran Mammals (Armadillos, Anteaters and Sloths)
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1 Institute of Experimental Pathology (ZMBE), University of Münster, Münster, Germany
2 Institut des Sciences de l'Evolution de Montpellier (ISE-M), UMR5554-CNRS, Université Montpellier II, Montpellier, France
3 Department of Biological Sciences, University of New Orleans, New Orleans, Louisiana, USA
Corresponding authors: Jürgen Schmitz (jueschm{at}uni-muenster.de), Institute of Experimental Pathology (ZMBE), University of Münster, Von-Esmarch-Str. 56, 48149 Münster, Germany, Tel.: +49 251 8352133, Fax: +49 251 8352134, Frédéric Delsuc (delsuc{at}isem.univ-montp2.fr), Institut des Sciences de l'Evolution (UMR5554-CNRS), Université Montpellier II, Place E. Bataillon, 34095 Montpellier cedex 05, France, Tel.: +33 4 67 14 39 64, Fax: +33 4 67 14 56 10
Received for publication May 14, 2007. Revision received August 7, 2007. Accepted for publication September 16, 2007.
Armadillos, anteaters, and sloths (Order Xenarthra) comprise one of the four major clades of placental mammals. Isolated in South America from the other continental landmasses, xenarthrans diverged over a period of about 65 million years, leaving more than 200 extinct genera and only 31 living species. The presence of both ancestral and highly derived anatomical features has made morpho-anatomical analyses of the xenarthran evolutionary history difficult, and previous molecular analyses failed to resolve the relationships within armadillo subfamilies. We investigated the presence/absence patterns of retroposons from 
7400 genomic loci, identifying 35 phylogenetically informative elements, and an additional 39 informative rare genomic changes (RGC). DAS-SINE elements, previously described only in the Dasypus novemcinctus genome, were found in all living armadillo genera, including the previously unsampled Chlamyphorus, but were noticeably absent in sloths. The presence/absence patterns of the phylogenetically informative retroposed elements and other RGCs were then compared to data from the DNA sequences of the more than 12 kb flanking regions of these retroposons. Together, these data provide the first fully resolved genus tree of xenarthrans. Interestingly, multiple evidence supports the grouping of Chaetophractus and Zaedyus as a sister group to Euphractus within Euphractinae, an association that was not previously demonstrated. Also, flanking sequence analyses favor a close phylogenetic relationship between Cabassous and Tolypeutes within Tolypeutinae. Finally, the phylogenetic position of the subfamily Chlamyphorinae is resolved by the non-coding sequence dataset as the sister-group of Tolypeutinae. The data provide a stable phylogenetic framework for further evolutionary investigations of xenarthrans and important information for defining conservation priorities to save the diversity of one of the most curious groups of mammals.
Key Words: DAS-SINE • retroposon • phylogeny • rare genomic changes • maximum likelihood
* These authors contributed equally to this work.
These authors share senior-authorship.
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