Ken Kinman comments on tracks

[John R. Grehan]

Ken Kinman wrote:

  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.

This is the possibility of reciprocity between the insights of biological
analysis of characters and the consideration of spatial characters.
According to some there can be no such reciprocal interplay because it is
'circular' and the source of all phylogenetic insight comes from biology
alone. Others such as Hennig and Rosa apparently thought differently.

>     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.

Seberg's study was supposed to be cladistic, so the distichus-goeppingeri
clade is presumably monophyletic in that respects. However, it was
intriguing to me also that this trans-Pacific link did not also include
Hawaii in any direct way.

>      I'm not sure why panbiogeography has been so controversial.

I'm sure historians can have a field day with this one. I think I have
mentioned earlier that the role of geographic space as an analytical
character in biogeography is rather outside the normal interests of
systematists and perhaps challenging to the notion that phylogeny is simply
biological. One can see this in Platnick and Nelson (1988) p. 412 that "To
us, an interpretation of characters stands or falls on its won merits,
regardless of proximity of distribution in time and space." A rather ironic
position given that these authors once claimed to have synthesized
panbiogeography with cladistics and Popper.

>Like cladistics, I think it is a useful tool when used carefully and in
>moderation.

I wonder if I am perhaps an 'immoderate' practitioner?

John Grehan
Frost Entomological Museum
Pennsylvania State University
Department of Entomology
501 ASI Building
University Park, PA 16802. USA.

Phone: (814) 863-2865
Fax: (814) 865-3048

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