Biogeographic memory

[P.Hovenkamp]

At 10:03 AM 9/10/01 -0400, you wrote:
(...)
>>As far as I understand Croizat, he looked at the distribution patterns
>>first, second and third. Only when he had established general patterns he
>>started looking for geological or geographic correlates. But he could be
>>quite content if he did not find one.
>
>Agreed
>
>>I know there must be a quotation somewhere to back me up on this...
>>Perhaps the following will suffice (from Croizat, 1968):
>>"The serious student understands, of course, that it is at times very
>>difficult, possibly even imprudent under present conditions to effect
>>correlations of detail between geology and biogeography (...)"(p. 218)
>>"Biogeography, if correctly used, is, in sum, a primary science in its own
>>right" (p. 225)
>
>Agreed. So in what way do you regard this as different to the approach I
>advocate?

Croizat correlated biological patterns to each other first, and only then
to geological features. Craw et al. correlate biological patterns to
geological features first, and then to each other.
To me, that is a big difference. In Craw et al.'s approach, it seems much
more difficult to arrive at general conclusions (about common geological or
geographical causes) that are not already implied in the premises.
Their major conclusion seems to be that the "major biogeographical regions
are (...) the modern ocean basins.". I think that proves my point.

>>>In what way is Croizat's approach being 'integrated' with phylogenetic data
>>>by vicariance biogeographer - particularly as vicariance biogeography seems
>>>to simply be a version of Darwinian biogeography in that it cannot predict
>>>biogeographic history without some kind of external (non-biological)
>>>criterion. Usually this criterion is concordance with some hypothetical
>>>historical sequence from geology or paleogeography - and in this respect is
>>>no different from traditional Darwinian biogeography.
>>
>>A fairly limited view of the developments in vicariance biogeography. Even
>>from reading Turner et al. it should be clear that there's more to it than
>>that.
>>I'm not going to argue whether vicariance biogeography has reached its
>>goal or not, but at least this line of approach tries to do two things
>>that Craw, Grehan and Heads' Panbiogeographys seems to have given up on:
>
>
>>1. It considers biological evidence independently from geological data
>>(treading in Croizat's steps)
>
>If this 'independence' is the only shared feature with panbigoeography it
>seems to me to be little substantiation vicariance biogeography developed
>from the method of panbiogeography.

One would have to check the literature from the '70's to find out in how
far vicariance biogeography actually derived from or was inspired by
Croizat. My statement is based on rereading Hull (1988).

>>2. It tries to incorporate the extra detail that resolved phylogenies
>>provide, especially with regard to the historical component (an expansion
>>of Croizat's method, which has no way to deal with historical information
>>of this kind).
>
>Without a homology relationship between biogeography and geology I don't
>see how this extra resolution can accomplish anything other than a
>non-spatial hierarchical arrangement of areas or taxa.

I do. May I refer to Hovenkamp, 1997, Cladistics 13: 67-79, and 2001,
Cladistics 17, in press?
But anyway, I was not dealing with exact methods, but with what the field
was trying to achieve.

>>They might not have minded so much if every point of criticism would not
>>have been accompanied by a sneer.
>
>I never noticed the 'sneer.'

Time for a few quotes again.
 From Croizat 1968:
(p. 117, about Corner's phytogeography): "Part of it (...) is steeped into
the juices of tradition, and Vansteenisian in its subservience to (...),
the unthinking stuff in sum which fills the larder of <<orthodox>>
<<phytogeography>> (...)"
(p. 165, about Backer & Van Steenis' account of Sonneratia for Flora
Malesiana): "Had a record of this kind been written, or checked, by a
taxonomist trained in solid biogeography (...)"
 From Croizat 1962:
(p. 129, discussing the interpretation of some floral structure): "Why not
bring in, too, pterodactyls, Ariovistus, "co-existence", the U.N.O.,
"Alliance for Progress, and the blessed like?""

But then again, it may be my imperfect understanding of the subtleties of
the English language, that prevents me from reading these statements as
simple expressions of well-meaning criticism.

>>. Van Steenis first came up with hypothetical "land bridges" (1962) to
>>explain the observed regularities in distribution patterns, which nobody
>>would believe in.
>
>So had many other biogeographers of his time and before. The question of
>Croziat's standing in the scientific community is, I belive, more than a
>simplistic appeal to his writing style. One potentially very important
>factor I believe is his being outside the North American-European
>institutional infrastructure. If he had not been cast out of the Arnold
>Arboretum because of political machinations perhaps history might have been
>very different.

 From a slightly different perspective: for an outsider (not being formally
trained in Botany), his impact has been considerable and lasting.