Ken Kinman comments on tracks
kinman at HOTMAIL.COM
Mon Jul 1 22:15:14 CDT 2002
I agree with Tom that this putative clade (and its putative
synapomorphies) should be reexamined. If Oreobolus distichus or goeppingeri
were found on any intervening islands (as in the fly genus Cymatopus), I
wouldn't find the distribution so strange.
Just because one cladist's analysis came up with this clade doesn't
make it holophyletic. Shultz's 1990 cladistic analysis embedded scorpions
within arachnids, and he couldn't do it without postulating various
reversals (and too great a faith in strict parsimony). I'm not saying that
this is the problem with Oreobolus, but your biogeographic analysis
indicates to me that this so-called clade could be based on homoplasies (and
would make a mess of your panbiogeographic analysis).
No matter how that particular issue might turn out, I find the absence
of Antarctica on such maps VERY disturbing. If Oreobolus was starting to
break up into clades during the Oligocene, Antarctica would probably be the
most important part of the puzzle. I would strongly suggest you plot the
distributions of Oreobolus on an Oligocene world map (or at least back to
the Miocene if "circularity of reasoning" has you worried).
I suspect that the main tract of Oreobolus is trans-Antarctic and that
it spread northward on both sides of the Pacific. *IF*
distichus-goeppingeri really is a clade, it is probably either an old
slow-evolving vicariant clade (with lots of extinctions having taken place),
or it is a recent clade with some bizarre dispersal event having taken
But I certainly wouldn't automatically assume that it really is a
clade just because one cladist's analysis came out that way (especially if
based on "selected" characters, as in some of Sereno's dinosaur phylogenies
which probably make tyrannosauroids too derived among other problems).
Otherwise you could be missing out on some "red flags" your panbiogeographic
analysis might be sending you. If it really is paraphyletic (or worse yet
polyphyletic), ANY biogeographic analysis which assumes holophyly would be
---- Cheers, Ken Kinman
>From: Tom DiBenedetto
>Date: Mon, 1 Jul 2002 14:41:39 -0400
>John R. Grehan wrote:
> > This is the possibility of reciprocity between the insights of
> > analysis of characters and the consideration of spatial characters.
> > According to some there can be no such reciprocal interplay because it
> > 'circular' and the source of all phylogenetic insight comes from biology
> > alone.
>I am not sure what you are getting at here. I don't think that anyone,
>cladists, would object to a re-examination of their character-based
>phylogeny if that
>phylogeny indicated sister-group relationships that are geographically
>bizarre. Such a
>re-examination however would entail a more-careful examination of the
>evidence, an effort to discover new characters, or perhaps a broadening of
>of the analysis with the inclusion of more taxa. It would not admit
>evidence into the analysis, because all phylogenetic insight does indeed
>the evidence of heritable characters (what you mean by "biology", I
>Is it the position of panbiogeographers that spatial distribution patterns
>allowed to influence the outcomes of phylogenetic analyses?
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