Ashlock was treated badly

[Curtis Clark]

At 02:07 PM 1/7/02, Ken Kinman wrote:
>The "Holo" in holophyletic explicitly indicates a "Whole" complete
>group, in contrast with monophyletic (mono means one, as in having one
>origin, which says nothing about the group being whole or complete).

Paraphyletic groups have a minimum of two origins: the origin of the
inclusive clade and the origin(s) of the clades excluded from it. (T'Pau,
one of Spock's mentors, says that to call such a group monophyletic is
illogical.)

>The strict cladists got their way, so
>they could brand paraphyletic groups as "non-monophyletic", and since they
>are "incomplete" they should be branded as unnatural and destroyed.

They *are* incomplete. Their incompleteness is in every sense but the most
trivial a result of ad hoc human intervention, so they are unnatural.
Unnatural groupings are not always bad (I think of the classification of
books in a library), and paraphyletic groups are not necessarily bad,
*unless they are presented as natural groups*. We strict cladists simply
believe you can't have it both ways. Either a classification is natural,
composed entirely of natural groups, or else it is artificial.

(By "trivial", I mean that *every* paraphyletic group is natural in the
sense that it can be described by boolean operations on clades, but since
our classifications don't admit to a multitude of overlapping groups, the
choice of a *specific* paraphyletic group and the rejection of others that
overlap it is artificial.)

>P.S.  And it strikes me as odd that Ashlock's attempt at precision should be
>regarded as illogical or unwarranted, and yet precision suddenly becomes
>important when cladists want to distinguish "adjacency" and "directionality"
>of character states.  In most fields of human endeavour, "ordering"
>encompasses both adjacency and directionality.

There are places in the California South Coast Ranges where the adjacency
of sediments is obvious, and consistent over wide areas. But, despite the
second law of geomorphology ("newer sediments overlay older ones"), the
directionality is not so obvious, since in other regions the same sediments
can be found in exactly the reverse top-to-bottom sequence. Subsequent
studies showed that tectonic activities had folded the sediments like a
taco, but initially there was no necessary relationship between adjacency
and directionality.

It seems to me that separating the two is a wise practice no matter what
historical usage says.


--
Curtis Clark                  http://www.csupomona.edu/~jcclark/
Biological Sciences Department             Voice: (909) 869-4062
California State Polytechnic University      FAX: (909) 869-4078
Pomona CA 91768-4032  USA                  jcclark at csupomona.edu