Info req.: molecules/morphology
kinman at HOTMAIL.COM
Mon Jun 26 19:35:07 CDT 2000
I did not discuss this issue in my 1994 book (The Kinman System), but I
definitely had to confront it. The SSU rRNA sequence of Verrucomicrobium
was so distinctive, that I made it the type genus of not only a new Order
Verrucomicrobiales, but also a new Class Verrucomicrobea. Bacteriologists
have followed suit since that time.
On the other hand, bacteriologists have prematurely named a group of
metabacteria (= archaebacteria) that haven't even been formally named at
generic level yet. Even more oddly, some call it Xenarchaea, while others
called it Korarchaeota.
I personally think they have really jumped the gun in this case,
because these forms are probably just distinctive forms of Crenarchaea. If
the new Bergey's Manual raises Crenarchaea to Kingdom Status, then this
group Xenarchaea (a.k.a. Korarchaeota) may well be ranked as a separate
Phylum, which is totally absurd in my opinion.
So in my view, the bacteriologists were several years too slow in
recognizing one major group (Class Verrucomicrobea), and several years
premature in recognizing the new metabacterial group (which I will no doubt
recognize as just another Order within Class Crenarchaea). We can't even
name this Order, because as far as I know, they have not even been given a
genus name yet. Furthermore, the supposed dictinctive nature of the SSU
rRNA of this group has almost surely been magnified by the Woesian
misrooting of prokaryotic phylogenies, but I don't think bacteriologists
have figured this out yet.
Whether such problems are cropping up at the level of genera or
families, I can't really say, not having the resources to tackle many such
problems below ordinal level. I would not surprise me in the least.
Both of these groups have been virtually based on the distinctive
nature of their SSU rRNA only, but I think they were too slow to formally
recognize the one, and have greatly overestimated the distinctiveness of the
other. Each case must be decided on its own merits, but in most cases, I
would say it would be best to wait for morphological confirmation. The
Verrucomicrobium case was highly unusual.
-----That's my 2 cents worth,
>From: Thomas Lammers <lammers at VAXA.CIS.UWOSH.EDU>
>Reply-To: Thomas Lammers <lammers at VAXA.CIS.UWOSH.EDU>
>To: TAXACOM at USOBI.ORG
>Subject: Info req.: molecules/morphology
>Date: Mon, 26 Jun 2000 15:19:28 -0500
>Can anyone suggest recent papers that address in any detail the idea that
>clades that emerge in phylogenetic analyses of molecular data require
>morphological or other non-molecular synapomorphies before it is practical
>to recognize them formally? I am particularly interested in commentary or
>theoretical papers on this topic, rather than primary research papers in
>which the topic had to be dealt with, though anything would be helpful.
>Thank you for your help.
>Thomas G. Lammers, Ph.D.
>Assistant Professor and Curator of the Herbarium (OSH)
>Department of Biology and Microbiology
>University of Wisconsin Oshkosh
>Oshkosh, Wisconsin 54901-8640 USA
>e-mail: lammers at uwosh.edu
>Plant systematics; classification, nomenclature, evolution, and
>biogeography of the Campanulaceae s. lat.
>"Today's mighty oak is yesterday's nut that stood his ground."
> -- Anonymous
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