Biogeographic memory

[John Grehan]

>
>The request for quotes suggests that John Grehan does not recognize this
>position as being one that is taken up in the book.

No it does not. All I intended here was to know specifically what Hovenkamp
had in mind when making his statements rather than speculating on my part.

>That is curious, considering the content of chapter 4, which starts with:
>"An understanding of geographical evidence is *basic* to interpreting the
>phylogeny, systematics and taxonomy of species and higher taxa", and in
>the same vein on the following page:

I do not see that as to mean that biogeographic analysis is not to be
informed by phylogenetic analysis based on other [non spatial] characters.

>"The panbiogeographic project (...) advocates that biogeographic analysis
>is a necessary *prerequisite*  for a coherent presentation of phylogeny
>and constructioin of a natural classification (...)" (p. 89). (*emphasis*
>mine).

Here I think the difference in perspective concerns what is a 'phylogeny.'
In my perspective a phylogeny is the evolutionary history of lineages.
Lineages have a biological and spatial history. A phylogeny that is
rendered simply as a set of biological relationships without incorporation
of spatial relationships is, to my mind, only a partial representation of
the phylogeny. A natural classification to my mind is one which is
cognizant of both biological and spatial relationships.

>The chapter then continues with defending the position that heritable
>characters and geographical occurrence can be treated with equal standing
>("Geographical distributions as a Systematic Character") and concludes
>with "(...)a natural classification can only be established after, not
>before, a biogeographic analysis." (p. 113).

Treating heritable [presume biological] characters and geographical
occurrence with equal standing in my view does allow for each to
potentially inform the other.


>Moreover, and pehaps more telling, Craw, Grehan and Heads give a great
>many examples and illustrations, but only a very small minority of these
>refer to explicit hypotheses about phylogeny. Most of this minority is
>taken up by examples in Ch. 4, and deal with the prediction of
>phylogenetic relations from biogeographic patterns. Phylogenetic data as
>input for biogeographic analysis is obviously not what the book is about.

Agreed, phylogenetic (biological) relationships is not the central theme of
the book.


>Would not that be enough to dismiss the claim that "their distiributions
>are not distinguishable according to their different means of dispersal"?

Not in my view.

>Perhaps this illustrates the rather arbitrary way in which Panbiogeography
>uses "similarity".
>Thus, the two distributions discussed here are treated as "similar",
>despite clear dissimilarities - as in other cases tracks treated as
>similar "Indian Ocean Baselines" can be as dissimilar as fig. 2-2
>(connecting India to Sumatra), 3-3 b (connecting Cape to S. Australia) or
>3-6  c (connecting Madagascar and India).

Since similarity of distribution range is not part of panbiogeographic
method the illustration of similar in the examples does not characterize
the way 'panbiogeography' uses similarity. Perhaps I should have asked Mayr
to illustrate his original assertions of 'totally' different distributions
(assuming he would have bothered to respond) and used his criteria for
illustrative purposes. Problems of similarity aside, the point remains that
dispersal ability is not a predictor of biogeographic homology.


>IMHO, hardly any issues warrant 400 pages. For one thing, it makes it so
>difficult to trace quotations that are referred to as (Croizat, 1968).

At least Croizat included extensive referencing in most of his major works.
However, if one were to read Croizat (1968) one would not need such an
index anyway.

>I've just obtained a copy of Croizat (1968, all 400 pages) from our
>library. To summarize this is beyond me at the moment, but a quick glance
>is enough to notice that this does deal with Wallacea in rather a big way.

Perhaps this is just a matter of a difference in perspective as to what
constitutes "rather a big way." And of course Croizat (1968) is not the
only publication by this author to deal with the region anyway.

  Perhaps it is yet too complicated to summarize?

It would depend on what one is looking for in the way of a summary. A
graphic summary is provided in Croizat's (1958) global map of dispersal for
example.

John Grehan