Article: A New Tree Of Life Allows A Closer Look At The Origin Of Species

A New Tree Of Life Allows A Closer Look At The Origin Of Species

In 1870 the German scientist Ernst Haeckel mapped the evolutionary
relationships of plants and animals in the first 'tree of life'. Since then
scientists have continuously redrawn and expanded the tree adding
microorganisms and using modern molecular data, yet, many parts of the tree
have remained unclear. Now a group at the European Molecular Biology
Laboratory (EMBL) in Heidelberg has developed a computational method that
resolves many of the open questions and produced what is likely the most
accurate tree ever. The study, which appears in the current issue of the
journal Science, gives some intriguing insights into the origins of bacteria
and the last common universal ancestor of all life on earth today.

"DNA sequences of complete genomes provide us with a direct record of
evolution", says Peer Bork, Associate Coordinator for Structural and
Computational Biology at EMBL, whose group carried out the project. "For a
long time the overwhelming amount of data (the human genome alone contains
enough information to fill 200 telephone books) has made it very difficult
to pinpoint the information needed for a high-resolution map of evolution.
But our study shows how this challenge can be tackled by combining different
computational methods in an automated process."

Bork's lab specialises in the computational analysis of genomes, and
recently they applied this expertise to the tree of life. Since all
organisms descend from the same ancestor, they share some common genes.
Francesca Ciccarelli and Tobias Doerks of Bork's group managed to identify
31 genes with clear relatives in 191 organisms, ranging from bacteria to
humans, to reconstruct their relationships.

"Even using such genes, you might get the wrong answer," says Ciccarelli.
"Organisms inherit most genes from their parents, but over the course of
evolution, a few have been obtained when organisms swapped genes with their
neighbours in a process called horizontal gene transfer (HGT). Obviously,
the latter class of genes does not tell you anything about your ancestors.
The trick was to identify and exclude them from the analysis."

Full Text at ScienceDaily
http://www.sciencedaily.com/releases/2006/03/060303111420.htm

Posted by
Robert Karl Stonjek


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