[Taxacom] Animalia or Metazoa?
Stephen Thorpe
s.thorpe at auckland.ac.nz
Thu Jul 23 23:14:34 CDT 2009
Ken: there is still a semantic problem, deriving largely from the fact
that the meanings of these higher taxon names aren't determined by
typification. The name Metazoa is arguably still a misnomer (issues
about sponges aside), since it means "higher animals", but includes
all animals if you think that Protozoa turned out not to be animals at
all! Once upon a time, Animalia included Protozoa and Metazoa (and
sponges). Protozoa were thrown out into "Protista". Two ways of
thinking about it:
(1) Protozoa were thrown out because they were discovered not to be
animals after all - in which case we can (?should) still use Animalia
for the rest; or
(2) Protozoa are animals, but animals aren't a clade, so we ought not
to use Animalia as a taxon name. Then Metazoa becomes the best name
for the old "Animalia" minus Protozoa. Effectively, it was discovered
that animals don't exist! Animals are a biphyletic concept, to be
assigned to the big Hennigian rubbish bin for non-monophyletic taxa...
Stephen
Quoting Kenneth Kinman <kennethkinman at webtv.net>:
> Hi Stephen,
> Well, I don't think that there is any question that Metazoa are
> "higher", i.e. more derived, than Protozoa (specifically Choanozoa).
> Phylogenetic neutrality is thus pretty much irrelevant. Same with
> Metaphyta with respect to Chlorophyta. Metazoa and Metaphyta are very
> popular names which have long been widely used, so any excess of
> popularity that Animalia and Plantae might presently enjoy is not (in my
> opinion) as important as precision (the former translate as "higher
> animals" and "higher plants", while the latter translate as just
> "animals" and "plants"). Plantae is thus probably better regarded as a
> synonym of Archaeplastida (which was proposed for the purpose of being
> more precise).
> As for the name Metabacteria not being phylogenetically neutral,
> NEITHER are the names Archaebacteria or Archaea. To be phylogenetically
> neutral, one should classify a single Empire/Domain/Kingdom called
> Prokaryota (or Bacteria) and not subdivide it into subkingdoms at all at
> this time (which would actually be fine with me). I'd be happy to list
> all the prokaryotic phyla and let different people code the
> relationships as they see them. However, even Woese himself seems to now
> believe that Eubacteria split off first and then the so-called
> Archaea/Archaebacteria (which would make the latter names not only
> phylogenetically biased, but biased in the wrong way, and thus
> misnomers).
> -----Ken Kinman
>
>
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