Jonathan Badger wrote:
>> One of the reasons ribosomal
> RNA is a popular molecule for estimating phylogeny is that it
> minimizes many of the problems given above. This is not to suggest
> that *only* ribosomal RNA is good for phylogeny, but genes should be
> chosen with some amount of care to minimize these problems.
This point is true. One of the main reasons the rRNA have been used for
phylogeny reconstruction (apart from ease of isolation, firstly using
RNA-directed technology and later using the PCR) is the idea that they
are directly vertically transmitted and not subject to lateral gene
transfer.......Until, Peter Sneath published in 1993 (see reference
below) the funny things might possibly have happened in the small
subunit ribosomal RNA gene in the Aeromonads (gamma proteobactria).
This is the only report to my knowledge of this kind of thing (E&OE) and
it is nearly impossible to detect a crossing over event unless it is
quite recent. However, the extension from that, has major implications
for ribosomal RNA phylogenies.
As far as we know, "ribosomal RNA....minimises many of the
problems...[associated with constructing organismal phylogenies from
other genes]", but lets be careful.
Sneath, P. H. A. (1993). Evidence from Aeromonas for Genetic
Crossing-Over in Ribosomal Sequences. International Journal of
Systematic Bacteriology 43(3): 626-629.
Dr. James O. McInerney Ph.D. Phone/Voicemail: +44 171 938 9247
Senior Scientific Officer, email:j.mcinerney at nhm.ac.uk
The Natural History Museum,
London SW7 5BD
Whenever I think of the past, it brings back so many memories...