Compromise in the air? (was: Boolean games)

Sat Mar 12 11:15:27 CST 2005

I have to disagree with you, Curtis.  Certainly, two different views of where reptiles stop and birds begin can coexist - only one may be right, but given that we don't know which one that is, both are hypotheses; there are many unresolved matters involving two or more coexisting hypotheses.  If two alternatives could not coexist, then we would have no disputes in our classifications.

The much discussed question about the closest link to humans, orangutan or chimp, is an example of coexisting alternative hypotheses, although perhaps not the best example.  Good grief, there are coexisting hypotheses about the relationships among seed plants!


Dick J.

----- Original Message -----
From: Curtis Clark <jcclark-lists at EARTHLINK.NET>
Date: Friday, March 11, 2005 11:30 pm
Subject: Re: Compromise in the air? (was: Boolean games)

> on 2005-03-11 19:17 Ken Kinman wrote:
> > Curtis, You're right, I should be thankful some strict cladists
> (like> yourself) have finally conceded that paraphyletic groups
> are natural.
> Shit is natural, too, but I don't want it in my kitchen.
> As I've said before, paraphyletic formal taxa don't play well with
> others. Choosing the dividing line between a paraphyletic taxon
> and an
> included clade is necessarily arbitrary ("anagenesis"
> notwithstanding).Certainly, a lot of decisions of which clades to
> name are also
> arbitrary. But because clades are nested, they can coexist (in a
> rankless system such as Phylocode, they can coexist *easily*, but
> that'sanother issue). Paraphyletic groups don't have that freedom; for
> example, two different views of where reptiles stop and birds begin
> cannot coexist. And so recognition of paraphyletic groups enforces a
> sort of hegemony. The Kinman System notwithstanding, basic textbooks
> that talk about Class Reptilia cannot simultaneously deal with
> Archosauria as a formal taxon *at any rank*.
> > And this may sound very strange coming from someone who has turned
> > strongly against PhyloCode, BUT HERE GOES.  I would probably support
> > a PhyloCode if it included provisions for occasional exceptions
> where> major formal paraphyletic taxa (explicitly marked) would be
> allowed> in order to foster stability and renewed harmony in the
> taxonomic> community.  Especially exceptions such as Bryophyta and
> Pteridophyta> in botany, Sarcopterygii and Amphibia in
> vertebrates, Prokaryota in
> > microbiology, and invertebrate phylogeny is still too poorly
> known to
> > determine what exceptions would be most important there.
> Unfortunately, this only makes the problem worse. Because
> Phylocode is
> unranked (and I agree with Norm Platnick that this is more of a
> shortcoming than an advantage), even a single paraphyletic group
> destroys the system (or, more specifically, destroys any
> non-intersecting properties it has), because it has the potential to
> intersect and thus preclude any other taxon (remember than in
> Phylocodethere is a fluidity in which today's "A is a subclade of
> B" can be
> tomorrow's "B is a subclade of "A" when new evidence is presented).
> Bryophyta and Pteridophyta are clades; including the liverworts in the
> former and the lycophytes in the latter was always a mistake, and
> when a
> solid traditional morphologist like Ernie Gifford became aware of the
> lycophyte mistake, he corrected it. Systematics has advanced by
> systematists correcting the mistakes of the past based on new
> evidence.It's one thing to champion the usefulness of paraphyletic
> groups; it's
> another thing to champion the usefulness of outmoded, unsupported
> conclusions.
> > And once a few PhyloCodists begin to compromise on this,
> I hope I've made it clear that they can't, even if they wanted to.
> For a
> system to be composed of groups that are simultaneously unranked and
> non-intersecting, they have to be nested. I think another failing of
> Phylocode is the insistence on non-intersecting groups (species of
> hybrid origin are members of two different lineages, for example), but
> that's another issue.
> --
> Curtis Clark        
> Web Coordinator, Cal Poly Pomona                 +1 909 979 6371
> Professor, Biological Sciences                   +1 909 869 4062

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