Themes > Science > Life Sciences > Generalities > Human Genome Project > Impact of Genomics on Taxonomy

Takashi Gojobori
Laboratory DNA Data Analysis, Center for Information Biology
National Institute of Genetics
1111 Yata, Mishima, Shizuoka, 411-8540, Japan


As the genome project has advanced, the complete genome sequence data is accumulating with enormous speed. So far, the complete genome sequence data for more than twenty microbial species has been made public. In order to elucidate the evolution of genomic structures, we made an attempt to compare complete genome sequences between different species, paying particular attention to the order of gene locations on the genome. One of the most significant findings by this attempt was that the genome had undergone tremendous rearrangement during evolution.

As a result, gene locations have been changed substantially in both lineages since their speciation. Moreover, some genes must have been transferred horizontally from other species. These observations imply that the genome possesses its own evolutionary plasticity by which the genome has a mosaic structure composed of genes of different evolutionary origins. The conventional molecular systematics utilizes phylogenetic trees which are constructed by use of a particular gene or a particular set of genes.

When the mosaic structure of the genome is taken into account, we must point out the possibility that the tree topology may vary with the gene or gene set used. It follows that the immediate conclusion from a phylogenetic tree may cause a wrong evolutionary relationship of OTUs (Operational Taxonomical Units). Although there is no easy solution to this problem, I would present several possible ways that systematics can use tree topologies in a reliable way.

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