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Cladistic Massive Retaliation
In the vain hopes of stopping this before it starts again...
Ron Oreinstein wrote:
>This kind of classification, you will notice, depends entirely on who an
>animal's ancestors were - it says nothing about what it looks like or how
>much it has changed.
And because of this, the groups which are formed by a cladistic
analysis are real groups (Gauthier and deQuiroz [sic] 1990). Groupings
based on morphological or functional differences do not constitute a real
entity in nature, but are an aritificial classification imposed by humans.
A clade, an ancestor and all of it's decendants, is an actual entity (ibid).
Non-cladists expect their groups to behave as if they were real
natural entities, which they are not. They are not units of evolution, and
are thus useless for the study of evolution. For example, Romer (1966) gets
rather wound about himself describing how every "reptile" decended from the
"Cotylosaurs", effectively obscuring the realtionships between the major
amniote taxa. This is certainly not a good way to go about the discussion
Rant-> And people say "evolutionary" taxonomies are inhererently more
stable. How much more stable a taxon can you get then one identified based
on a common ancestor and it's decendants. Sure the composition may change,
but the taxon name always describes the same concept. Non-cladists seem to
be forever changing the definition, composition, or diagnostic characters of
all of their taxa. Is *that* stable?
Jeff Martz wrote:
> Cladistics makes the assumption that evolution is a process of
>imply adding to the list of prexisting characters, without taking into
>account features that are lost or very radically modified. For example,
This is incorrect. Phylogenetic systematic practice does not make
a statement about characters, it says that taxa should be based solely on
the principle of common decent (ibid).
Phylogenetic *analysis* is predicated on the assumption that
phylogenetic relationships can be discerend through the analysis of
*shared*derived* characters. If the derived state is that a former character
has been lost or radically modified, that is fine. Thus, your initial
statement is incorrect.
>the fact that reptiles are a group of animals with traits inherited from
>a common ancestor, but ignores the fact that some features, such as
>scales and ectothermy, were lost in mammals and birds. Yes, I know
It certainly does *not* ignore these characters. These are
synapomorphies which support the higher clades Mamalia and Aves (although,
in both cases, the actual point at which the character state transforms is
>that endothermy and hairs are modifications of these, but who can tell
>me that recgnizing that they are HIGHLY modified in mammals and birds,
>but shared by all reptiles, is not evolutionarily important? Cladists
As I said, this is clearly recognized, but if one is basing one's
taxa on common decent, it is irrelevant. Common decent removes an element
of human judgement from the systematic proceedure. *WHO* is making the
determination that these advanced characters justify a new paraphyletic
taxon? *YOU* are. Cladists do not assume this responsibility. They do not
define taxa on the basis of their own oppinion of what constitutes a "HIGHLY
modified" structure. They do use their own judgement on characters, but so
does everyone else. Cladists end up with real groups. Paraphyletic groups
are not real.
>on this list frequently say that thier system is the only taxonomy that
>takes evolutionary relationships into account, but in this regard
>I feel that cladistics is strongly lacking.
I'm afraid you have missed the point. You did not say a single
thing about evoltionary relationships, you only talked about morphological
distance, which has *nothing* to do with the phylogeny. There isn't even an
objective standard for establishing morphological distance (Sereno 1990, in
_Dinosaur Systematics_), nore is one likely to appear which is applicable to
fossil specimens. Morphological distance is not useful information to
anyone except someone who needs a card catalog. Even then, Romer 1966
highlights the difficulty of deciding who is or isn't advanced enough to go
in your paraphyletic taxon.
> A truly comprehensive phylogenetically based taxonomy NEEDS
I am sorry, you are again missing the point. A truly phylogenetic
taxonomy _cannot_ have paraphyletic groups, because paraphyletic groups are
not real entities. They are purely constructs of our minds.
> Into the abyss...
"You never fought for anything in your life, now FIGHT!"
The Cladistic Assassin
| Jonathan R. Wagner "You can clade if you want to, |
| Department of Geosciences You can leave your friends behind |
| Texas Tech University Because your friends don't clade |
| Lubbock, TX 79409 and if they don't clade, |
| *** firstname.lastname@example.org *** Then they're no friends of mine." |
| Web Page: http://faraday.clas.virginia.edu/~jrw6f |