Molecular evolution and the genomics revolution

Molecular phylogenies based on rRNA sequences have served a pivotal role in defining three major organismal domains, Archaebacteria, Bacteria and Eukaryotes and their branching pattern, the tree of life. However, particularly when systematically analyzing complete genome sequences, inconsistencies have emerged that are best explained by lateral transfer of genetic material. Best known is the integration of bacterial genetic information into the nuclear genome of the eukaryotic cells, during the transformation of alpha-proteobacterial and cyanobacterial symbionts into mitrochondria and chloroplasts. In addition, more recent evidence suggests that also the genomes of Eubacteria and Archaebacteria have a mixed heritage. The importance of genomics for further exploring the origin and evolution of living beings will be discussed: only a minute portion of the biological diversity on earth has so far been explored: the genomics era has barely begun.