Kingdoms

[Ken Kinman]

Brian,
     Oooops, yes, I definitely meant prefix (my brain was more depressed
yesterday than I realized).
     I should note that I do not claim that the Three Domain system is
"incorrect", but that it is inappropriate and misleading.  It does greatly
exaggerate the differences between eubacteria and metabacteria
("archaebacteria"), detracting from the much more fundamental differences
between prokaryotes and eukaryotes, and Ernst Mayr has been arguing these
and other points since 1990 (when the discredited 3 Urkingdoms were
spin-doctored into 3 Domains).
     But what really concerns me most is the misrooting and distortion of
phylogenies when the Three Domains are treated as holophyletic (when only
Eukarya is and the other two are not).  The results are inaccurate
classifications, and many misinterpretations of the polarity of important
characters (e.g., thermophily).  Whenever higher taxon names create
confusion and slow scientific progress (e.g., "Fungi" or "Archaea"), I think
they should be discarded.  That is one reason we don't apply priority rules
to higher taxa.
      I am convinced that we will discover what the earliest bacteria were
like, but that Three Domains is a serious impediment to progress in
understanding the history of prokaryotic evolution, the evolution of
photosynthesis, and truly understanding how metabolic pathways developed
(among other things).
                          -----Ken Kinman
P.S.  The terms "primitive" or "lower" organisms never have bothered me.  I
find prokaryotes just as interesting as mammals or spiders or angiosperms.
However, prokaryotes preceded eukaryotes, and protists preceded higher
plants and animals (evolution does have a "gradistic" element to it, even if
it is politically incorrect to admit it).  And let's face it, humans do
place a hierarchy of importance on organisms.  You can kill millions of
bacteria (and be praised for your cleanliness), killing your neighbor's dog
will get you in a lot of trouble, and killing your neighbor can mean life in
prison or death.  So terms like Higher and Lower seem to be a natural result
of human biases.
*******************************************************
Brian wrote:
>      The concept of "higher" and "lower" has a rather gradistic aspect to
>it implying that the "lower" organisms never developed further. I suggest
>that all current organisms must be successful to survive, with their
>ancestors dying out - irrespective of whether single cells or mutlicellular
>organisms.
>                <snip>
>     There is probably too much discussion on which system is "correct",
>when we may never be able to prove any of them. Despite being a "higher"
>organism man may never be able to work out exactly what the first
>(primitive) cells looked like.
>
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