[Taxacom] Molluscan phylogeny (overview)

John Grehan jgrehan at sciencebuff.org
Fri Mar 13 11:59:12 CDT 2009

This sounds awfully like data manipulation. As for groups being probably
real because they are consistently' supported across multiple data sets,
this is problematic because it depends on what kind of data. Phenetic
methods, for example, consistently supported reptiles as a natural
group, but cladistic methodology showed that the group was not 'real' at
all. That is particularly pertinent given that aligned homologies do not
exist in nature and that the individual homologies are determined as a
consequence of an overall similarity algorithm that somehow balances
gaps and substitutions. I'm not sure I would like to rest a phylogenetic
reality on imaginary homologies.

John Grehan

> -----Original Message-----
> From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-
> bounces at mailman.nhm.ku.edu] On Behalf Of Dr. David Campbell
> Sent: Friday, March 13, 2009 11:40 AM
> To: taxacom at mailman.nhm.ku.edu
> Subject: Re: [Taxacom] Molluscan phylogeny (overview)
> Molecular data don't actually significantly support polyphyly of
> bivalves; rather, monophyly versus polyphyly or paraphyly is not
> resolved.  I believe the best way to get a good feel for this sort of
> thing is to play around a lot with the data yourself.  Don't just run
> one analysis on your data.  Rather, keep running various analyses,
> at and adjust the alignments, add in additional taxa, etc.  Groups
> are consistently supported across multiple data sets and analyses are
> probably real; the novel result in your latest analysis might not be.
> --
> Dr. David Campbell
> 425 Scientific Collections Building
> Department of Biological Sciences
> Biodiversity and Systematics
> University of Alabama, Box 870345
> Tuscaloosa AL 35487-0345  USA
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