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Date: Fri, 04 May 2001 21:30:42 +0200
From: David Marjanovic <david.marjanovic@gmx.at>
To: PhyloCode mailing list <phylocode@ouvaxa.cats.ohiou.edu>
Subject: Re: subscribers (& "lophotrochozoans")
----- Original Message -----
From: <kinman@usa.net>
To: <phylocode@ouvaxa.cats.ohiou.edu>
Sent: Wednesday, May 02, 2001 5:54 PM
Subject: subscribers (& "lophotrochozoans")
> Taxonomic suppression? I'm not suppressing anything, nor am I
arguing
> against formal taxon names (see David Hillis post). But as professionals
we
> have to show some restraint. I recognize formal taxa that have stood the
test
> of time,
That's a bit subjective. What if I say that your Reptilea has totally failed
the test of time, and that your Thecodontiformes are even worse? You can say
"no", in which case I -- devil's advocate -- can repeat the above sentence,
and so on ad nauseam. You can say "lots of people are using it", then I can
say "all of those are wrong", and I can always find someone who won't use
it. Can we test such ideas (science...)?
> and I do not arbitrarily discrimate against paraphyletic groups
> (although they are small in number compared to the holophyletic groups
which I
> recognize).
Same as above -- I can say you arbitrarily recogize some arbitrarily
selected paraphyletic groups (and add the marker to make them
semi-para/holophyletic).
> And I use {{markers}} to show where exgroups are removed.
Paraphyletic
> groups with such markers render them holophyletic in an informational
sense,
> and cladistic sister group information is not discarded as it is in
> traditional Linnean classifications.
Very good, I think, but how do you decide what to include in the ex- and
what in the ingroup?
> 48 phyla, 269 classes, 1,719 orders (and an estimated 15,000
> families)----I am hardly against the recognition of formal taxa.
Here I will say that 48 phyla for all life is far, far too few, there are
many more taxa that deserve phylum rank. "Deserve", of course, is arbitrary,
as above.
> We need them
> for communication and a relatively stable evolutionary framework.
Sure!
> Kingdom Metazoa and Phyla Chordata, Echinodermata, Mollusca, etc.,
these
> are uncontroversial clades that have stood the test of time. These are
the
> kinds of groups I formally recognize at every level of the Linnean
hierarchy
> (including mammalian orders, although I did emend the endings for reasons
I
> have explained elsewhere).
Do you formally recognize Dinosauria? Theropoda? Tetanurae? Gnathostomata?
Tetrapoda? Amniota?
> Lophotrochozoa, on the other hand, is extremely controversial.
Naming
> such a formal taxon on a single gene (and a handful of organisms) was
> immediately and rightly criticized for various reasons by Conway Morris,
> Cohen, Gawthorp, Cavalier-Smith and Winnepennickx (Science, 272:282).
> Hillis claims their are "hundreds" of synapomorphies for
Lophotrochosa
> (many of which are individual bases in 18S rDNA sequences), but he
apparently
> chooses to ignore a vast literature that contradicts that it is a clade.
And
> not surprisingly, the very same molecular analyses do not "strongly"
support a
> deuterostome clade (which is far less controversial). That should have
raised
> a big red flag.
Here I must stop playing devil's advocate -- is there morphological evidence
for Lophotrochozoa? What specifically is the evidence against? (I haven't
read the Science paper yet.)
Why suddenly Lophotrochosa? What is this?
One synapomorphy of Lophotrochozoa is apparently an insertion in a hox gene.
Dicyemids (the remaining "Mesozoa") have this, therefore Mari Kobayashi,
Hidetaka Furuya and Peter W. H. Holland concluded that "Dicyemids are higher
animals" in Nature 401, 762 (21 October 1999). Specifically: "This
'spiralian peptide' [...] has only been reported from the Antp orthologue in
lophotrochozoans, a group that includes annelids, ribbon worms [are these
Nemertini/-ea?], brachiopods and planarians (recently assigned to this
clade)."
> In my opinion, lophotrochosozoan rDNA is conservative and
plesiomorphic,
> and that two clades (deuterostomes and ecdysozoans) arose independently
from
> it, each having rDNA which diverged from the more conservative
> lophotrochosozoan form.
The paper that found Acoela as the basalmost bilaterians,
Iņaki Ruiz-Trillo, Marta Riutort, D. Timothy J. Littlewood, Elisabeth A.
Herniou, Jaume Baguņā: Acoel Flatworms: Earliest Extant Bilaterian
Metazoans, Not Members of Platyhelminthes, Science 283, 1919 -- 1923 (19
March 1999),
carefully excludes all taxa with 18S rDNA that evolves too fast for useful
comparisons, such as most acoels, many flatworms, all nematodes,
chaetognaths, "mesozoans", gnathostomulids, acanthocephalans, and 1 of the 2
sequenced rotifers. Yet --
(Bilateria)
|--Acoela
`--(Coelomata?)
|--Deuterostomia
| |--Chordata
| `--+--Hemichordata
| `--Echinodermata
`--(Protostomia)
|--Ecdysozoa
| |--+--Nematomorpha
| | `--Arthropoda
| `--+--Kinorhyncha
| `--Priapulida
`--Lophotrochozoa
`--+--Gastrotricha
`--+--(Platyhelminthes, explicit to ~order
"level")
`--"Rest of the lophotrochozoan taxa"
(not more explicitely shown :.-( , contains Mollusca, Annelida, Nemertini,
Sipuncula, Brachiopoda, Entoprocta, Bryozoa, Phoronida, Echiura,
Pogonophora)
names in parentheses don't occur in the paper
Outgroups: Placozoa: *Trichoplax* "the one and only" *adhaerens*, Porifera:
*Scypha ciliata*, Cnidaria: *Anemonia sulcata*, *Tripedalia cystophora*
BTW, here we have several examples of clades that are unnamed because nobody
needs names for them. This will change if (ever) they become subject to
intense discussion, and I think they should be named in this case, just for
ease of discussion.
> and I worry that this casts a cloud over cladistic analysis in
> the long term.
Cladistic analyses have put turtles either with a clade of basal sauropsids
into Anapsida, or into Sauria; whales either next to or deeply within
Artiodactyla. I can't see the word Whippomorpha, coined in 1995, casting
clouds over cladistic analysis. Don't worry, test hypotheses :-)
> I would not even recommend the regular use of the informal
> "lophotrochozoan"--- it is far preferable to refer to them separately as
> trochozoans (or the slightly more inclusive spiralians?) and
lophophorates.
> --------Ken Kinman
Where would Platyhelminthes and Gastrotricha fit? All in "Spiralia"?
> P.S. As for Rodentiformes and Lagomorphiformes, I am convinced they do
form a
> glires clade (and continue to code them as such). I would certainly never
> combine two such useful and stable taxa into a formal Gliriformes.
Because naming Glir(iform)es requires giving them order rank and forgetting
Rodentia and Lagomorpha in your system.
BTW, I take it from Society of Vertebrate Paleontology meeting
abstracts there are fossil mammals that fit into Gliriformes (the name
exists outside the Kinman System, apparently this is the crown group) but
not into either Duplici- or Simplicidentata (which include Lagomorpha and
Rodentia, respectively).
:-)