More on Biogeographic memory

John R. Grehan jrg13 at PSU.EDU
Fri Oct 12 13:56:30 CDT 2001


>May I suggest that you also subsume panbiogeography under "form systematics" ?
>- 1) you connect spatially nearest locations for one taxon. Thus it has to
>be a taxon first... This is "form systematics", at least alpha-taxonomy.

Form systematics is about biological homologies. Panbiogoeography is about
spatial homologies and spatial correlation

>- 2) you connect spatially nearest localities of the distribution networks
>of two sister groups. Thus they have to be sister groups first.

They can be if one wants to map sister group relations. One may also draw
tracks within a taxon solely on minimum distance criteria irrespective of
sister group relationships.

>This is
>"form systematics", called phylogenetic systematics, even if elementarily
>condidered as disconnected sister-groups relationships, but you envisaged
>the possibility of intregating the hierarchy of sister groups in a recent
>message (... this could lead you very close to vicariance biogeography...).

The difference here remains the use of spatial homology and correlation
whereas vicariance biogeography does not.

If one defines systematics broadly enough it could include biogeography.
Certainly in the practice of many systematists biogeographic homology is
determined by systematic (biological) homology so the biogeography may rest
on arcane arguments of systematic analysis.


>Seems that differences with vicariance biogeography will have to be found
>elsewhere than in "subsuming to systematics", or did I miss something ?

Yes the differences are in concepts of homology. In drawing attention to
such differences I am not precluding use of phylogenetic methods and
analysis of common or different patterns of phylogenetic relationships.
Morrone has suggested using panbiogeography for spatial homology and then
form systematics to examine the biological relationships within particular
spatial arrangements (sorry Morrone for any misrepresentation). Morrone
also showed how apparent incongruence of form relationships may represent
the presence of more than one track relationship that can be separated out
using panbiogeography.


>Maybe you are addressing only the way "elementary biogeographic units" are
>defined, one-taxon spatial networks in Panb. rather than areas of
>endemicity in Vic.Biog.?

Both one-taxon or multi-taxon networks I think.


>Otherwise, Panbiogeography subsumes to systematics some way. Guess this is
>logically unavoidable, given that we deal with geography of TAXA.

Or we deal with the taxa of GEOGRAPHY!

John


>Pierre

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

Frost Museum
http://www.ento.psu.edu/home/Frost/index.html




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