Cyperales or Juncales?
jrc at ANBG.GOV.AU
Wed Jul 10 11:09:42 CDT 2002
>Species phylogenies (cladograms) are, at heart, a collection of character
yes... inferred but plausible ones...
>But they are more than that, because heritable
>characters qualify as valid evidence of taxic history - because such
>descend within isolated lineages. This is also why spatial characters,
>which do not descend in isolated lineages, do not qualify as evidence of
maybe it is just a question of scale (temporal and/or spatial?) - in many
organisms (plants especially) the chances are fairly likely that progeny
will end up growing in the same place as their parents who were most likely
to be growing in the same place as their parents, and the progeny of the
progeny are most likely to end up in the same place. Even though it may
be controlled by dispersal mechanics and the inverse square law rather than
genetics, the net result looks and smells very much like inheritance and
descent - if you have a disjunct pair or suite of sibling species, it is
most unlikely that one will spontaneously pop up in the others turf, just
as it is unlikely that one will spontaneously acquire the characters that
distinguish it from its relatives. These are observable facts and it is
difficult to see why they should be ruled out as evidence. Obviously in
time populations move... just as in time populations evolve...
Having said all that, I still get very uneasy, and even suspicious, when I
see a key couplet that contains the words:
a) Plants found in X...
b) Plants found in Y...
~ Jim Croft ~ jrc at anbg.gov.au ~ 02-62465500 ~ www.anbg.gov.au/jrc/ ~
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