Universal phylogenetic tree

Figure 2. Universal phylogenetic tree determined from rRNA sequence comparisons. A matrix of evolutionary distances (99) was calculated from an alignment (260) of representative 16S RRNA sequences from each of the three urkingdoms. The length of the lines is proportional to the phylogenetic difference. (Reproduced with permission from ret 16. Copyright 19. American Society for Microbiology.)...

The repartition in the universal phylogenetic tree of life, of the direct and indirect pathways for Gln-tRNA and Asn-tRNA biosynthesis in bacterial lineages, is shown in Figure... 

The universal phylogenetic tree, therefore, is not an organismal tree at its base but gradually becomes one as its peripheral branchings emerge. The Universal Ancestor is not a distinct entity. It is, rather, a diverse community of cells that survives and evolves as... 

In the still-valid taxonomic model, microorganisms can be classified into the three domains ofeubacteria, archaea, and eukaryotes. The three domains branched off very early in evolution, united by a common ancestor the corresponding picture of the relationships between the domains and kingdoms is termed the universal phylogenetic tree . 

C. R. Woese, Interpreting the universal phylogenetic tree, Proc. Natl. Acad. Sci. USA 2000, 97, 8392-8396. 

FIGURE 2 Rooted universal phylogenetic tree highlighting major components of the microbial loop. CFB indicates the Cytophaga-Flavobacter-Bacteriodes lineage. (Adapted from Woese, 1994). 

Studies on the pathways of central metabolism of the archaebacteria take on special significance when it is realised that, from the universal phylogenetic tree in rooted form, Woese et al. [66] have proposed that the domain of the archaebacteria be known as archaea to denote their apparently primitive nature, especially with respect to the eukaryotes. Furthermore, within the archaea, thermophily is regarded as the ancestral phenotype. 

Fig. 2. Universal phylogenetic tree in rooted form, showing the three domains, based upon the corresponding tree in ref. [49] and more recent results concerning eukaryote phylogeny (M.L. Sogin, personal communication). The position of the root was determined by the Dayhoff strategy , described...

Woese, C. R. Interpreting the universal phylogenetic tree. Proceedings of the National Academy cf Sciences. USA, 97 (2000), 8392-6. 

Figure 1. Universal phylogenetic tree based on comparative 16S rRNA sequencing showing the relationship of representatives of the three primary lines of evolutionary descent. Sequence differences through regions of unambiguous alignment (about 950 nucleotides) were corrected for multiple nucleotide substitutions per site and these estimates of sequence divergence (mutations fixed per sequence position) used to infer the phylogenetic tree as previously described (26). (Reproduced with permission from Ref. 23. Copyright 1986 Cell Press.)...

The principal characteristics of the rRNAs and of their corresponding genes, as well as the advantages to study rRNA sequences, are summarized below. Then are surveyed the most important results obtained from comparisons of rRNA sequences for the building of the so-called universal phylogenetic tree, but also for the determination of the relationships between less distantly related species. 

---