Deleporte and Kinman on the Pacific
kinman at HOTMAIL.COM
Thu Jul 4 17:00:13 CDT 2002
I guess I am going to have to try and get a copy of Seberg's 1988
analysis sometime before commenting much more on Oreobolus. But from the
evidence I have seen, the Cenozoic radiation of Poales was largely from the
south into the north (which was more devastated by the K-T event), and
Oreobolus seems to reflect that pattern.
My approach to "reciprocal illumination" is more of the
"brainstorming" kind which can't be reduced to algorithms and strict
criteria (at least not at present). If panbiogeography as presently
practiced cannot accomodate testing using narrative approaches, then it's
too restrictive for my tastes (and I will have to borrow from it without
embracing it fully). Reminds me of arguing with strict cladists who argue
all characters MUST be weighted equally, and if they have 10 characters
supporting their phylogeny, and I only have 5 characters supporting mine,
then strict parsimony says that they are correct unless I can come up with
more characters (no matter how good mine are or how subject to homoplasy
theirs may be). I am not easily impressed by long lists of tiny character
changes (such as those which dinosaurologists produce to support some of
their favorite clades), especially when many characters are non-independent.
In any case, I believe your Oreobolus paper will be fatally flawed if
your maps maintain that mid-Pacific baseline (with its big solid black
square), especially if Seberg is right about distichus-goeppingeri being a
derived clade (and thus having little relevance to the biogeography of all
the earlier speciation in Oreobolus).
A more southerly baseline (as in your initial Oreobolus track map)
makes more sense to me, except that I would go even further south, directly
from New Zealand (or Tasmania) to the southern tip of South America (and not
via Tahiti). Once Oreobolus is found in the Antarctic fossil record,
spanning tracks that are even more southerly and shorter can be shown via
that land bridge. That's the narrative I predict future evidence will bear
out for Oreobolus (and a lot of other taxa).
------- Ken Kinman
P.S. It was suggested to me privately that O. furcatus might have been
spread to Hawaii and Tahiti by birds (perhaps through their droppings?). I
don't know enough about Oreobolus dispersal mechanisms to really rule out
humans or birds or anything else, especially if we don't know how long ago
such dispersals occurred. If O. furcatus previously existed in areas
further west, those populations may have been wiped out by feral pigs (a
problem in Hawaii, and perhaps the reason for its present rarity on Tahiti).
Anyway, this is one plant genus that really has aroused my interest.
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