RE: Philosophies for Character Ordering

[Mike Milbocker <mmilbocker@psdllc.com>]

David Marjanovic wrote:

>>Ordering only means to arrange the states of a character in a line. It
does
not make any assumptions about which end of the line is the plesiomorphy.
This is for the outgroup to decide. If the outgroup has a long tail, the
ordered character will be equivalent to the assumption that the tail
gradually got shorter; if the outgroup has a short tail, the ordered
character will be equivalent to the assumption gradually got longer.
(Ignoring the possibility of reversals.)

It's exactly the same as with binary characters.<<

Well to be literal, it can't be exactly the same as binary characters,
otherwise there would be no advantage to using ordered states.

It's the line itself, as well as the direction of the line that is encoded
with assumptions about evolution, albeit quite reasonable assumptions. What
seems to be invoked here is a parsimony of transformation, which is quite
different from Occam's Razor, on which parsimony is based.

If one is going to allow fewest transformations to order the states, why not
use stratigraphic data, spatial proximity, fitness of preservation. Quite
reasonably, one could devise ordering paradigms to encode Bakker's entire
Heresies into a set of characters. It all depends on where one is willing to
draw the line. I'm not objecting to its use, I'm just cautioning that if one
uses ordered states one can no longer claim that the cladogram is the
simplest structure depicting character associations. It's predictive power
will be dependent upon the reality of the ordering assumptions. And I would
hope such assumptions would be clearly stated.

Regards,

Mike Milbocker