Branching order of bacterial phyla (Woese, 1987)

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There are several models of the Branching order of bacterial phyla, one of these was proposed in 1987 paper by Carl Woese.[1]

The branching order proposed by Carl Woese was based on molecular phylogeny, which was considered revolutionary as all preceding models were based on discussions of morphology. (v. Monera).[2] Several models have been proposed since and no consensus is reached at present as to the branching order of the major bacterial lineages.[3]

The gene used was the 16S ribosomal DNA.

Tree[]

The names have been changed to reflect more current nomenclature used by molecular phylogenists.

Archaea + eukaryote

Bacteria

Thermotogae

Chloroflexi

Deinococcus-Thermus

Proteobacteria

Cyanobacteria

Firmicutes

Actinobacteria

Planctomycetes

Chlamydiae

Spirochaetes

Bacteroidetes

Chlorobi

Note on names[]

Despite the impact of the paper on bacterial classification, it was not a proposal for change of taxonomy. Consequently, many clades were given official names. Only subsequently, this occurred: for example, the "purple bacteria and relatives" were renamed Proteobacteria.[4]

Discussion[]


Last universal common ancestor[]

The root of the tree, i.e. the node of the last universal common ancestor, is placed between the domain Bacteria (or kingdom Eubacteria as it was then known) and the clade formed by the domains Archaea (formerly kingdom Archaebacteria) and Eukaryotes. This is consistent with all subsequent studies, bar the study by Thomas Cavalier-Smith in 2002 and 2004, which was not based on molecular phylogeny.[5]

Eukaryotes are a mosaic of different lineages:

  • The genome in the nucleus descends from the first organelle-less eukaryote, the "urkaryote" a sister species to the ancestral archeon
  • The mitochondria are organelles that descended from the proto-mitochondrion, a species of Rickettsiales (Alphaproteobacteria) (v. Reclinomonas and retortamonads).
  • The chloroplasts are organelles of cyanobacterial origin.

Consequently, in Woese (1987) the group is referred to as urkaryote.

The clade composed of Archaea and the nuclear genome of eukaryotes is called Neomura by T. Cavalier-Smith[5]

See also[]

Footnotes[]

References[]

  1. ^ Woese, CR (1987). "Bacterial evolution". Microbiological Reviews. 51 (2): 221–71. doi:10.1128/MMBR.51.2.221-271.1987. PMC 373105. PMID 2439888.
  2. ^ Olsen GJ, Woese CR, Overbeek R (1994). "The winds of (evolutionary) change: breathing new life into microbiology". Journal of Bacteriology. 176 (1): 1–6. doi:10.2172/205047. PMC 205007. PMID 8282683.
  3. ^ Pace, N. R. (2009). "Mapping the Tree of Life: Progress and Prospects". Microbiology and Molecular Biology Reviews. 73 (4): 565–576. doi:10.1128/MMBR.00033-09. PMC 2786576. PMID 19946133.
  4. ^ Stackebrandt; et al. (1988). "Proteobacteria classis nov., a name for the phylogenetic taxon that includes the "purple bacteria and their relatives"". Int. J. Syst. Bacteriol. 38 (3): 321–325. doi:10.1099/00207713-38-3-321.
  5. ^ a b Cavalier-Smith, T (2002). "The neomuran origin of archaebacteria, the negibacterial root of the universal tree and bacterial megaclassification". International Journal of Systematic and Evolutionary Microbiology. 52 (Pt 1): 7–76. doi:10.1099/00207713-52-1-7. PMID 11837318.
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