Wednesday, August 20, 2008

Evolutionary Tree of Life reviewed by crabsallover

In 1866 (just seven years after publication by Charles Darwins' "The Origin of the Species" in 1859) Haeckel's published his 'Tree of Life' showing the relationship between Plantae, Protista and Animalae.

In 1977 Carl Woese (wikipedia & homepage & A New Biology for a New Century (2004)) hypothesis was that organisms are subdivided into three domains (Archaea, eukaryote, bacteria) not just two domains (eukaryote and prokaryote) .

"Having defined Archaea as a new domain, Woese redrew the taxonomic tree. His three-domain system, based upon genetic relationships rather than obvious morphological similarities, divided life into 23 main divisions, all incorporated within three domains: Bacteria, Archaea, and Eucarya. Archaea are neither Bacteria nor Eukaryotes. Looked at another way, they are Prokaryotes that are not Bacteria. "(source: Carl Woese - wikipedia)
The Universal Tree of Life is understood by differences in ribosomal RNA. (source: fig 1, PNAS).

19th August 2008: In a Press Release, which was picked up by DailyTech, then Richard new research published in PNAS next week confirms that Archaea (extreme thermophiles (high temperature loving) or halophiles (high salt loving)) are more closely related to Eucarya (animals, plants, fungi) than Bacteria. (see diagram).

Woese was the first to look for signs of evolution in the ribosome, where genetic information is translated into proteins. In the mid-1970s, he and his colleagues found consistent differences in the sequence of nucleotides that spell out the RNA of the ribosome in bacteria and archaea.

These "molecular signatures" were so pronounced that Woese concluded that the archaea comprised a separate domain of life, distinct from bacteria and eukarya (animals, plants, fungi and protists). His classification system is now widely accepted.

The original work by Carl Woese was reported in Microbiological Reviews (1987).

Carl Woess (fig 4 above) indicates the relationship between the Archaea, Eucarya and Bacteria was not well established.

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