Archive for March, 2009

Just a little more information…

Historical Biogeography is concerned with relationships among and between species —the true genetic relationship of taxa. It deals with evolutionary processes occurring over millions of years on a large scale.

The five biogeographic methods are: dispersalism, phylogenetic biogeography, panbiogeography, Cladistic biogeography, and parsimony analysis of endemicity.

Cladistic biogeography assumes a correspondence between taxonomic relationships and area relationships, where comparisons between area cladograms derived from different taxa allow one to obtain general area cladograms. The most important Cladistic biogeographic procedures are: component analysis, Brooks’s parsimony analysis, three-area statements, and reconciled trees.

 

 

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Introduction to BPA concepts

Brooks Parcimony Analysis (BPA), as other methods used in historical biogeography, has been received criticism from some authors. BPA does not have a computer program to be performed, and the data are prepared manually.

The historical biogeography methods of analyses are divided in two categories: a priori and a posteriori methods. BPA is considered a posteriori method. The major difference between those methods is the sister group relation. A posteriori methodology forbids changes or distortion of the area sister group. This information is gotten from the taxon phylogenetic tree.

Both methods have the same null hypothesis – vicariant speciation – and make the assumption that phylogenetic and distribution data of taxa are informative for the reconstruction of the historical relationships among their areas of distribution. However, I wondered how they work with sympatric species…

The answer for my question has not consolidated yet in my mind, but Platnick & Nelson (1978) proposed two assumptions that were improved by other authors. Actually those assumptions have been proposed to sympatric and widespread species.

 

I still need to read more about it and look for more papers related to.

 

Any help or comments are welcome.  J

 

Platnick, NI & Nelson, G. 1978. A method of analysis for historical biogeography. Systematic Zoology 27: 1-16.