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.



  1. Juanita Said:

    Yes Cissa, as the null hypothesis is vicariant speciation, one could only reject it under a very “strict” scientific scenario and thus, the other types of speciation wouldn’t be accepted just because of its rejection. In that sense, sympatric speciation or dispersal (speciation by founder effect) would have to be tested separately under another method.

    I think actually there is a very big controversy related to these methods, many of them tend to be inductive, making many people argue that they are not “science”. But also, there is a difficulty in developing accurate methods under deductive reasoning.

    Anyway, we should continue reading more about this subject :S

  2. cwaichert Said:

    Yep, you’re right!
    But the method’s improved has been fast in last few years and, I believe that if molecular techniques, we will find a “more scientific” way to study historical distribution of the organims.

{ RSS feed for comments on this post} · { TrackBack URI }

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: