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Open Access Highly Accessed Research article

Site specific rates of mitochondrial genomes and the phylogeny of eutheria

Karl M Kjer1 and Rodney L Honeycutt2*

Author Affiliations

1 Rutgers University, Department of Ecology, Evolution, and Natural Resources, Blake Hall, 93 Lipman Drive, New Brunswick, New Jersey 08901-8524, USA

2 Pepperdine University, Natural Science Division, 24255 Pacific Coast Hwy, Malibu, California 90263-4321, USA

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BMC Evolutionary Biology 2007, 7:8  doi:10.1186/1471-2148-7-8

Published: 25 January 2007

Abstract

Background

Traditionally, most studies employing data from whole mitochondrial genomes to diagnose relationships among the major lineages of mammals have attempted to exclude regions that potentially complicate phylogenetic analysis. Components generally excluded are 3rd codon positions of protein-encoding genes, the control region, rRNAs, tRNAs, and the ND6 gene (encoded on the opposite strand). We present an approach that includes all the data, with the exception of the control region. This approach is based on a site-specific rate model that accommodates excessive homoplasy and that utilizes secondary structure as a reference for proper alignment of rRNAs and tRNAs.

Results

Mitochondrial genomic data for 78 eutherian mammals, 8 metatherians, and 3 monotremes were analyzed with a Bayesian analysis and our site specific rate model. The resultant phylogeny revealed strong support for most nodes and was highly congruent with more recent phylogenies based on nuclear DNA sequences. In addition, many of the conflicting relationships observed by earlier mitochondrial-based analyses were resolved without need for the exclusion of large subsets of the data.

Conclusion

Rather than exclusion of data to minimize presumed noise associated with non-protein encoding genes in the mitochondrial genome, our results indicate that selection of an appropriate model that accommodates rate heterogeneity across data partitions and proper treatment of RNA genes can result in a mitochondrial genome-based phylogeny of eutherian mammals that is reasonably congruent with recent phylogenies derived from nuclear genes.