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Microbial evolution
Author(s):
V. Kunin, L. Goldovsky, N. Darzentas, C. A. Ouzounis
Institution:
European Bioinformatics Institute - EBI
Year:
2005
URL:
http://genome.cshlp.org/content/15/7/954.full
Project Description:
EBI researchers have changed our view of 4 billion years of microbial evolution. Christos Ouzounis and colleagues have gained intriguing quantitative insights into how gene families are transferred, not only 'vertically' through passage from one organism to its progeny, but also 'horizontally' through the exchange of genetic material between distantly related organisms. Since the time of Darwin, the evolutionary relationships between organisms have been represented as a tree, with the common ancestors at the base of the trunk and the most recently evolved species at the tips of the branches. Microbiologists have argued for a long time that this representation doesn't really hold true for microbes, which often exchange genes among different species. Their claim has been that the evolution of these organisms is better represented by a net.

To get a grip on horizontal gene transfer, they used a method called GeneTrace. The data generated by GeneTrace allowed them to draw 'vines', representing horizontal-genetransfer events, connecting branches on the evolutionary tree. In all, more than 600,000 vertical transfers are observed, coupled with 90,000 gene loss events and approximately 40,000 horizontal gene transfers.

This image shows a bird's-eye view of the tree of life, showing the vines in red and the tree's branches in grey [Bacteria] and green [Archaea]. The last universal common ancestor is shown as a yellow sphere.

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Manuel Lima | VisualComplexity.com