dispersal fantasy

[Ken Kinman]

Dear All,
     John criticized using the absence of a match (between area cladograms
and postulated geological history) as being evidence of dispersal.
     In some important cases, I think absence of such a match could be
indicating that the postulated cladograms are wrong (and that
panbiogeography can perhaps help bring attention to such mistaken
assumptions), especially regarding disjunct ranges on opposite sides of the
Pacific.
      For instance, in Grehan's recent paper (Journal of Biogeography,
28:413-429), Figure 4a shows a long Pacific track (for Ascaphidae)
connecting New Zealand and the U.S. Pacific Northwest.  This immediately
made me wonder if Leiopelma really forms a holophyletic group (clade) with
Ascaphus.  And sure enough, when Grehan posted a link to his amphibian maps
(TAXACOM, June 12), the paraphyletic nature of that grouping is shown (with
Leiopelmatidae as a separate family) and that long mid-Pacific tract is
gone.  It would indeed be sad if cladists were to propose long distance
transoceanic dispersal rather than questioning their cladograms in such a
case.
     And in looking at Grehan's Oreobolus maps (paper in preparation, in a
link posted June 10), I sort of half-wondered if something similar could be
true of the O. distichus-goeppingeri "clade".  I haven't read Seberg's
paper, but I wonder if this so-called clade could be based on
symplesiomorphies (or other homoplasies).  Anyway, it's something I think
would be worth considering, especially given Seberg's own reservations
overall.
      I'm not sure why panbiogeography has been so controversial.  Like
cladistics, I think it is a useful tool when used carefully and in
moderation.  But I have always tended to look for commonalities embedded
within most controversies.  If you just look at the differences,
controversies are almost certainly going to remain unresolved.  Well, I
guess that is enough sermonizing for today (to-DAAAAAAYYYYYEE).
         -------- Ken Kinman



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