Bioinformatics in Microbiology 1

Lamarck (1809) was first to present an evolutionary tree. The tree was based on bifurcating lines connecting different invertebrate animal groups as well as vertebrates such as fish, birds, mammals and subdivisions within the mammals. Darwin (1859) used a hierarchical tree-like structure to illustrate 1) common ancestry among organisms, 2) alternating processes of variation and selection, and 3) geological stratification of organisms. The hierachial tree and Darwin’s conceptual ‘Tree of life ” was used by Häckel (1875) graphically to illustrate the relationships between higher organisms. Hennig (1950, 1966) developed concepts to statistically analyze biological data in a phylogenetic perspective. Phylogeny sensu stricto is dealing with the ancestral relationships of species. Currently “phylogeny ” is used about numerous biological relationships between populations, genes and groups of organisms also. Data expected to include phylogenetic information are DNA or protein sequences of homologous genes and morphological characters shown to be homologous. Data with dubious phylogenetic information are most restriction patterns (PFGE, AFLP, ribotyping) and most DNA hybridization data (micro-array, Southern blot etc.). Phylogenetic analysis involving molecular sequence comparisons has at least four uses