Wednesday, May 10, 2006

Viruses and mammalian phylogenetics

Will the virus-based news never cease? A recent article (Kriegs et al. 2006) in PLOS Biology reports on a phylogeny of placental mammals constructed from markers left by retroviruses (retroposons). Carl Zimmer has more background on this technique; suffice to say that using retroposons is an extremely accurate method for reconstructing phylogenies. The resulting phylogeny is below:

Phylogeny of mammals from PLOS Biology
"Positions of Retroposed Elements as Landmarks of Evolution on the Bayesian-Based Placental Evolutionary Tree from Murphy et al. The resultant tree is consistent with previous studies in most aspects. Note that the positions of afrotherians and xenarthras have been reversed, based on the presence of two retroposon insertions at node 2. Gray balls represent single insertion events. Supported splitting points are labeled with Arabic numerals. Superordinal clades, in the order shown, were established by Waddell et al. and supported by several major studies, and are labeled with Roman numerals. The taxa shown represent only those from which we sampled LINEs and LTRs. Dotted lines indicate nodes in need of further confirmation. Asterisks represent retroposon evidence from the literature for monophyly of Afrotheria, Primates, Rodentia, and Cetartiodactyla."

I'm quite pleased that this phylogeny supports the idea (seen in other phylogenies as well) that rats and mice are closer (evolutionarily) to humans than dogs or cats (both of which are in Carnivora). Take that, dog and cat lovers!

Kriegs JO, Churakov G, Kiefmann M, Jordan U, Brosius J, et al. (2006) Retroposed Elements as Archives for the Evolutionary History of Placental Mammals. PLoS Biol 4(4): e91 (full-text, PDF)

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