Mr Fortuner connection modem
fortuner at MATH.U-BORDEAUX.FR
Fri Apr 7 07:13:55 CDT 1995
It looks that wing size (suggested by Robin Leech) is an ordinal character
(with states ordered as = no wing/wing buds/brachyptery/full size wings) which
is linked to a real number character (wing length). On the other hand, mode of
locomotion (with several states including flight) looks to me like a promising
nominal character (although this is not a morphological character). Does it
have ISV (intraspecific variability)?
Curtis Clark said "It seems to me that
*any* two-state character is implicitly ordered" but there are in fact many
binary (2-states) characters that cannot be ordered, including all the
characters describing the presence/absence of a structure.
Kirkendall sent several very promising examples. Is there a plant taxonomist
who can confirm that this pins and thrums stuff is nominal? On the other hand,
color and shapes have been disqualified as being disguised ordinal characters.
He also suggested behavioral characters and host range.
So we now have
several behavior/ecological characters which are both nominal and
intraspecifically variable, but still no confirmed ISV for a morphological
nominal character (if there is such a thing). I should modify my original
"A truly nominal MORPHOLOGICAL character cannot be present in
a valid species in more than one state"
I wonder, if nobody can find a true
nominal character (except presence/absence) and if all qualitative characters
can be ordered (or at least transformed into an ordinal character), should not
this have some consequences for ordination methods?
fortuner at math.u-bordeaux.fr
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