Ken Kinman comments on tracks

[Ken Kinman]

John,
     I am not saying Oreobolus had to originate in Antarctica.  It could
have originated in Chile and crossed Antarctica into southern Australia.  Or
perhaps vice versa.  I'm just saying Antartica is probably the land bridge
that helps explain their current distribution.  Either way, I would bet it
spread north from Australia to New Guinea and from Chile to Central America.
     And I don't think the absence of that putative Oreobolus "clade" from
Hawaii (or any other mid-Pacific islands) should be merely footnoted as
"intriguing".  To me this is a red flag that is almost screaming out for an
explanation.  This is especially true since you begin with this
distichus-goeppingeri "clade", and work your way down the cladogram.  The
apparent similarity to the Cymatopus tract may be just a fluke, and the
historical path to that distribution may be much different.
     What I am arguing is that I think panbiogeography is an important tool,
and if you are going to use Oreobolus as an example, it would be highly
advisable to seriously "second guess" (and reevaluate) Seberg's cladogram
(especially since he himself apparently worried about homoplasy in his
analysis).  Otherwise this example could end up hurting (rather than
helping) panbiogeography.  That your overall map for Oreobolus has a
mid-Pacific line, but no south Pacific lines at all, seems highly misleading
(made worse by the absence of Antarctica on your maps).  If Antarctica had
also been covered by ice in the mid-Cenozoic, perhaps you could justify this
(but this is not the case, and I think you are omitting a very important
piece of biogeographic background information).  Antarctica is just as
important to southern disperal as the Bering Strait is to northern disperal,
perhaps more so.
      And finally, just to make my position clear in context to the
discussion of others in related threads, I certainly wouldn't advocate
entering biogeographic information into a cladistic analysis.  They should
be kept separate and used to independently check one another (and combining
them could also increase the danger of circularity).  Biological proximity
should be given more weight, but biogeographic proximity should not be
ignored (since the hypothetical biological proximity may be flawed).  So I
agree that taxonomy should not be placeless.  We need all the information we
can get.
        ------- Cheers,  Ken Kinman


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