Andrew Meade (University of Reading, Reading, U.K.) provided access to computing resources, and part of this work was carried out by using the resources of the Computational Biology Service Unit from Cornell University, which is partially funded by Microsoft Corporation. Munirul Islam (Wayne State University, Detroit, MI) provided computational support. We thank Wen-Hsiung Li (University of Chicago, Chicago, IL), Wilfried W. de Jong (University of Nijmegen, Nijmegen, The Netherlands), Nathaniel M. Pearson (Wayne State University), two anonymous reviewers, and the PNAS editorial board for comments and suggestions that greatly improved the manuscript. This research was supported in part by the Intramural Research division of National Institute of Child Health and Human Development, National Institutes of Health, Department of Health and Human Services and National Science Foundation Grant BCS-0550209. We acknowledge the sources of the unpublished genomic data, including: Baylor College of Medicine Human Genome Sequencing Center (cow; http://www.hgsc.bcm.tmc.edu/projects); the Broad Institute (rabbit, elephant, tenrec, and armadillo); and the U.S. Department of Energy Joint Genome Institute (frog).
Abbreviations: MP, maximum parsimony; ML, maximum likelihood; NJ, neighbor-joining.
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Freely available online through the PNAS open access option.
Author contributions: D.E.W., J.C.O., R.R., and M.G. designed research; D.E.W., M.U., J.C.O., and G.L., performed research; D.E.W., M.U., J.C.O., G.L., V.L., S.G., O.G., and M.G. analyzed data; and D.E.W., M.U., J.C.O., L.I.G., R.R., and M.G. wrote the paper.
The authors declare no conflict of interest.
This article contains supporting information online at www.pnas.org/cgi/content/full/0704342104/DC1.
© 2007 by The National Academy of Sciences of the USA