Woese's ideas

[Mike Crisp]

There has been a lot more research on the basal clades of life than Ken
Kinman's attack on Woese implies.  Many genes have been sequenced and
analysed, and there is some support for each of the three possible
relationships among Bacteria, Archaea and Eucarya.  Support for monophyly
of these groups is equivocal too.  However, there is considerable support
for Woese's hypothesis.  See the following review:

Williams, D. M. and T. M. Embley (1996). "Microbial diversity: Domains and
kingdoms." Annual Review of Ecology and Systematics 27: 569-595.

Here is their abstract:

        With the discovery of the eukaryote nucleus, all living organisms
were neatly divided into prokaryotes, which lacked a nucleus, and
eukaryotes, which possessed it. As data derived directly from the genome
became  available, it was clear that prokaryotes were comprised of two
groups, Eubacteria and Archaebacteria. These were subsequently renamed at
the new taxonomic level of Domain as Bacteria and Archaea, with the
eukaryotes  named as the Eucarya Domain. The interrelationships of the
three Domains are still subject to discussion and evaluation, as is their
monophyly. Further data, drawn from various protein sequences, suggest
conflicting schemes, and resolution may not be straightforward.
Additionally, Bacteria and Archaea as well as Eucarya are largely based on
organisms already in culture. Investigation of the potentially enormous
quantity of uncultured organisms in nature is likely to have as
broad-ranging implications as the exploration of new protein sequences.

Further to Magnus Liden's comments on using duplicated genes to root the
tree of life, here is a reference which discusses the general approach,
with examples:

Weston, P. H. (1994). Methods for rooting cladistic trees. Models in
Phylogeny Reconstruction. R. W. Scotland, D. J. Siebert and D. M. Williams.
Oxford, Clarendon Press. 52: 125-155.




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Dr. Michael D. Crisp
Senior Lecturer in Plant Systematics
Division of Botany & Zoology
Australian National University       Phone int+ 612 6249 2882
Canberra, ACT 0200, Australia         Fax int+ 612 6249 5573

On sabbatical at the Australian National Herbarium till 9 Dec 1997.
Phone +612 6246 5128
Email <Mike.Crisp at anu.edu.au>

  WWW http://online.anu.edu.au/BoZo/profiles.html
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