pink-haired clade (was "going offlist")

["Ken Kinman" <kinman@hotmail.com>]

Tim,
    I don't really fret much over the rank of most taxa, because I 
generally follow what others do (taking into account tradition, stability, 
but new discoveries as well that may warrant occasional changes).  Aves has 
always been a Class and will remain as such even if BCF turns out to be true 
(and there is a consensus that Aves should be expanded).  It has nothing to 
do with *superiority*, but rather divergence and diversification (and 
whether paleontologists like it or not, extant groups sometimes get the edge 
over those that are non-extant, but this is a minor consideration compared 
to divergence).
    However, since you made the comparison, I should also note that the gap 
between Eubacteria and Metabacteria ("Archaea") is also filling in (just as 
the theropod-bird gap has filled in).  And although I recognize a Phylum 
Metabacteria (it is indeed different), raising it to a Kingdom (much less 
Domain) is unwarranted and misleading-----it is as if you raised Aves to 
Phylum level, and we all agree that this would be unwarranted and unwise.   
Some constraints are needed to keep classifications balanced.  Furthermore, 
if you then used this "Phylum" Aves as an outgroup to Phylum Chordata, the 
whole chordate tree would be a ludicrous mess (reptiles evolving into 
amphibians and then to fish, and a whole lot of other distortions and 
reversed polarities).  That is essentially what is happening in 
bacteriological systematics.  Metabacteria is an ingroup, and using it as an 
outgroup to Eubacteria is mucking up the whole tree.
    Now, I'll start with your pink-haired girl and then generalise from 
that.  We have a mutant girl, the first ever with a recessive pink-hair 
gene.  Pink hair has such survival value that all her descendants soon far 
outnumber the descendants of her four siblings put together.  It becomes 
convenient to classify all the pink-hairs as a family separate from all her 
normal-haired relatives.
1   Family Brown-hair
        Genus Brown 1
        Genus Brown 2
        Genus Brown 3
        {{Family Pink-hair}}
        Genus Brown 4
_a_  Family Pink-hair (very prolific)
        Genus Pink 1
        Genus Pink 2
        Genus Pink 3
        Genus Pink 4
        Genus Pink 5
    You can easily see that the ancestor of the pink-hair clade came from 
the Brown-hair family.  It's not that I regard pink hair as "superior" to 
brown hair, but it is a convenient way to classify and to reflect a degree 
of information on diversity and divergence.  If the pink-hairs diverged in a 
whole lot of other characters as well (or if brown-hairs go extinct), I 
could bump pink-hairs up to Order level (leaving a second place-marker at 
family level, so we don't lose track of the sister-group information of 
where the pink-hair ancestor came from).  You could easily convert the above 
into a phylogenetic classification, but unfortunately biological evolution 
is far more complex than one clear-cut character change (and we are working 
from a known phylogeny above, which also made it easier).
    Phylogenetic taxonomists feel constrained by the Linnean hierarchy 
because they want to pack way too many of their phylogenetic hypotheses into 
"formal" nomenclature and classification.  Unfortunately phylogenies are 
unsettled and controversial (and will be for a long time), and therefore 
these restraints are useful in checking the serious side-effects of purely 
cladistic classifications.  PhyloCode will relax these restraints.  I 
believe stable phylogenetic information should be encoded in a somewhat 
constrained classification of formal names (maintaining usefulness, and 
providing the continuity of tradition whenever possible), and all the rest 
of the information should be encoded informally (coding that can reflect 
alternative hypotheses and newly acquired knowledge and new hypotheses).
    And as much as cladists hate the idea, a small percentage of formal 
taxa must be paraphyletic (semi-paraphyletic in my system, so the sister 
group information is not lost).  We can quibble how many is optimal, but 
taking it to zero is far too costly.  Mike Keesey has noted that informal 
paraphyletic groups are allowed in the phylogenetic system, but the 
side-effects of pure cladism are too high to justify excluding formal 
paraphyletic groups altogether (and that is where cladists and eclecticists 
clash most forcefully).  The price is too high and only gets higher with 
time.  Cladists either ignore these "costs" or claim they will go back down 
in time, but I see it as overexuberant optimism and not realistic (and not 
surprisingly, cladists think the same thing about my approach).
    Anyway, as Benton has noted, PhyloCode (and its relative lack of 
constraint) will lead to chaos in nomenclature (that will probably make 
today's mess look like a picnic).  I understand what PhyloCode hopes to 
accomplish, but believe those hopes are built on unstable ground.  Sorry for 
breaking my New Year's Resolution concerning PhyloCode, but a lot of us see 
a nomenclatural disaster in the making.
                 ------Ken Kinman
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