That is why skeptics doubted that researchers could ever hope to work out the evolutionary history of bacteria. But now, thanks to the availability of sequenced genomes for groups of related bacteria, and a new analytical approach, researchers at the University of Arizona demonstrate that constructing a bacterial family tree is indeed possible.

Nancy Moran, Emmanuelle Lerat, and Vincent Daubin propose an approach that begins by scouring genomes for a set of genes that serve as reliable indicators of bacterial evolution. This method has important implications for biologists studying the evolutionary history of organisms by establishing a foundation for charting the evolutionary events, such as lateral gene transfer, that shape the structure and substance of genomes.

Bacteria promise to reveal a wealth of information about genomic evolution, because so many clusters of related bacterial genomes have been sequenced--allowing for broad comparative analysis among species--and because their genomes are small and compact.

In this study, the researchers chose the ancient bacterial group called gamma Proteobacteria, an ecologically diverse group (including Escherichia coli and Salmonella species) with the most documented cases of lateral gene transfer and the highest number of species with sequenced genomes.

The results support the ability of their method to reconstruct the important evolutionary events affecting genomes. Their approach promises to elucidate not only the evolution of bacterial genomes but also the diversification of bacterial species events that have occurred over the course of about a billion years of evolution.

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Contact: Barbara Cohen
bcohen@plos.org
415-624-1206
Public Library of Science
15-Sep-2003