3TA (correction)

[Don.Colless at CSIRO.AU]

David Willams wrote:
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Don Colless understands 'character' to have "a pretty widespread usage
(a set of mutually exclusive attributes - or, if you wish, a Hennigian
transformation series)."  So when, in the past, fins 'transformed' into
limbs, because the 'fins' vanished from view the limbs must be
considered something new altogether (exclusive); limbs are usually
considered to be modified fins. They are modified. In that sense the fin
is still present; fin and limb are inclusive. The notion of 'exclusive
attributes' seems to demonstrate (or promote) the non-evolutionary
nature of binary data. Don Colless noted in his paper (Syst. Zool. 34:
229-233, 1985) "Problems in the term 'character' seem to have surfaced
first in the field of numerical taxonomy" (from p. 229). Indeed. And
there they reside.
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This is a neat example of the "character = part" usage, which of course
doesn't mesh at all with my usage. And of the curious metaphysical
notion, that the fin is still present in the limb. I recall an argument
with Gary Nelson, who insisted that a creature descended from elephants,
but which lacked a trunk, REALLY still had a trunk. O.K., if it makes
you comfortable to think such things, who am I to object - just as long
as the taxonomy still gets done.

I must note that anyone who prepares a data-matrix, for processing in,
for instance, the PAUP program, is implicitly using my own usage of
"character". The rows of the matrix represent taxa, the columns
characters, and entries in the cells are states. That a taxon displays a
given state is, in my usage, an "attribute". 


      Don Colless       
      CSIRO Div of Entomology,
      GPO Box 2600, Canberra, ACT, 2601,
      Tel: 02-62464270,
      Email: don.colless at csiro.au
      Tuz limunz est miens envirun



> -----Original Message-----
> From: David Williams [mailto:dmw at NHM.AC.UK]