Darwinian and panbiogeographic frameworks

[John Grehan]

Stuart Poss wrote:

>I suggest you read it and decide if the panbiogeographic problems you are
>studying can not be accounted for by predictions expected of Darwin's theory
>of evolution by means of natural selection.

I have not made this kind of inference. The phenomena studied in
panbiogeography
can are are accounted for by the general predictions of natural selection.

 Knowing little of the specific
>biological systems you are talking about, I would be most interested to learn
>just what particular phenomena and biological systems lead you to conclude
>they can not be explained by Darwin's central tenant.

Its not so much a matter of "cannot be explained" as it is that they can also
be explained in other ways, and these explanations are derived from the
application of a biogeographic method that leads to novel predictions of
facts that were not anticipated by Darwinian theory of natural selection.

  I know of no evidence that would force me to disagree with Darwin's central
>tenant, yet you suggest you have such evidence.  I, for one, would like to
>look at it.

Evidence is a matter of individual judgement. I would never claim to have
evidence
on anything that would "force" such a disagreeent. What is evidence for one
may not
be for another. There may be nothing in panbiogeography that will constitute
evidence to the contrary of Darwin. G. G. Simpsion never  changed his mind
about
continental drift, despite the "evidence".

If you are interested to read on the subject its now packaged in the
following
book:

Panbiogeography: tracking the history of life (1999). R. C. Craw, J. R.
Grehan,
M. J. Heads. Oxford University Press, New York.

If you wish to take issue with any of the content on this list I will be happy
to address them to whatever point I can.
>
>Darwin observed that the Galapagos fauna is unique because of a variety of
>effects that occured in time that led to differential selection among
>organisms occupying the islands,

My understanding is that he did not observe this differential selection, but
interpreted the process this way.

 and that for the most part, these organisms
>are most closely related to those he saw on the mainland.

One does not have to be a Darwinist to recognize this fact. To be a bit more
precise, its only a majority of the Galapagos organisms that are most
closely related to those on the mainland, but it is possible that Darwin only
saw those of the majority relationship.

 It is unclear what
>theory you refer to when you seem to imply that Darwin was incorrect to
>interpret the existence of the geographic variation in such features as other
>than a consequence of differential selection upon these geographic variants

Historically the theory has been termed orthogenesis (the meaning of this
being widely misrepresented by Darwinists, including Gould). It has
potential modern counterparts in the theory of molecular drive.

>or that his theory in some way is insufficient to explain a particular fact
>of biogeography.

It was in sufficient in that it did not lead to corroborated novel
predictions about
biogeography or geology.

Certainly, unknown to either Darwin
>or Hooker, there existed early invasions of microbial organisms into the
>bodies of other organisms that can confound the principles and techniques of
>biogeographic analysis,

This is an interesting point as I am not aware of panbiogeographic
principles and techniques being confounded by this process.

>However, it is unclear what aspect of your theory is necessary, beyond that
>posited by Darwin, that would more efficiently predict the organization of
>biotic diversity in general.

The book may clarify.


>Nonetheless, he was correct in his fundamental assertions, with regard to the
>consequences of explaining known morphological variation.

Perhaps, perhaps not.

  It is for this
>reason that understanding the precise phylogeny of life is so vitally
>important to the study of causal processes in biological systems, including
>the correct historical interpretation of their biogeography.

One does not have to be a selectionist to have this view of phylogeny.

I suspect that if one is a committed Darwinist, panbiogeography isn't going
to make any difference to most practitioners, and the converse is likely
true. I raise panbiogeography as an issue for those who are still floating
around
with respect to what evolutionary ideology might interest them. I would not
want
to impose panbiogeography on anyone else.

I will check on the Gould article and perhaps make additional comment.

Please send me citations of your biogeographic work on scorpaenoid
fishes if that will not cause undue inconvenience.

John Grehan