Árvores na web da vida: existem, mas os ramos...

Trees in the Web of Life

Kristen S Swithers, J Peter Gogarten and Gregory P Fournier
Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Road, Storrs, CT 06269-3125, USA

Journal of Biology 2009, 8:54doi:10.1186/jbiol160

The electronic version of this article is the complete one and can be found online at: http://jbiol.com/content/8/6/54

Published: 13 July 2009
Abstract

Reconstructing the 'Tree of Life' is complicated by extensive horizontal gene transfer between diverse groups of organisms. While numerous conceptual and technical obstacles remain, a report in this issue of Journal of Biology from Koonin and colleagues on the largest-scale prokaryotic genomic reconstruction yet attempted shows that such a tree is discernible, although its branches cannot be traced.

Minireview

The Tree of Life (ToL) is a widely used metaphor to describe the history of life on Earth. While Darwin argued that the 'Coral of Life' may be a more apt description (since only the surface remains alive, supported by the dead generations beneath it), relationships between organisms based on shared characters are best organized using the schematic representation of a tree. Use of molecular markers, in particular small-subunit ribosomal RNA, have allowed this metaphor to be extended to microorganisms; however, this has also presented unique challenges for notions of phylogeny and evolution. One of the most significant challenges is the impact of horizontal gene transfer, which causes genes that coexist in a genome to have different molecular phylogenies [1]. Despite these challenges, the increasing ease with which genomes can be sequenced has reinvigorated attempts to use genomic information to reconstruct the ToL.

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