[Taxacom] Usefulness vs convenience (Protista)
kennethkinman at webtv.net
Mon Dec 20 21:35:00 CST 2010
You seem to be saying that my classifications
(like the one for Kingdom Protista) are like a "mish-mash of apples and
oranges", and if so, could you clarify what you mean by mish-mash? Using
words more precise than mish-mash, how would you characterize such
eclectic classifications. Unnatural? or Natural (but arbitrary)?, or
some other combination of adjectives?
As for a paraphyletic group being merely a synchronic (present-day)
view, and I'm not sure I would totally agree with that, I don't think
this is that big of a problem (especially for higher ranked paraphyletic
taxa). The 5 generally-recognized Kingdoms of life were well-established
and fairly well-diversified by the beginning of the Carboniferous, so if
I were living then instead of now, I would have still recognized a
paraphyletic Kingdom Protista with three exgroup Kingdoms. The youngest
Kingdom (Metaphyta) would have been less diverse than today (since
angiosperms hadn't evolved), but it would have still been diverse enough
to merit 3 phyla (Bryophyta, Pteridophyta, and Spermatophyta), and the
fourth Phylum Magnoliophyta (angiosperms) would have been rather diverse
by the Cretaceous.
And Classes Mammalia and Aves were already fairly
diverse by the end of the Cretaceous, so a paraphyletic Reptilia was
already justifiable by that point. Of course, much of the diversity of
Mammalia and Aves at that time has not yet been found in the fossil
record, and much of that diversity was wiped out by the end-Cretaceous
extinction, with the surviving taxa reradiating into new taxa in the
Paleocene and Eocene. Aves is younger than Mammalia, but still had a lot
of enantiornithean-type diversity in the Cretaceous (which then went
extinct, and replaced by a radiation of the neornithine survivors in
Paleocene and Eocene).
So I don't think one is being merely synchronic
(present-day view only) if the exgroups to Kingdom Protista were diverse
by the beginning of the Carboniferous and the exgroups to Class Reptilia
were diverse by the Cretaceous. Or perhaps I am misinterpreting what
you meant that paraphyletic taxa are synchronic (present-day only)?
Richard Zander wrote:
If you try to mix classifications based on
patterns of evidence (phylogenetics) and classifications based on
theories of evolution of a group (evolutionary systematics) you will
always get a mish-mash of apples and oranges. A paraphyletic group is a
synchronic (one-dimensional present-day) view of a diachronic (through
time) evolutionary process. The phylogenetic view is from well-supported
evidence and the evolutionary view is theory. Only the last is science.
The first is artificial.
More information about the Taxacom