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.




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.