Lucy in Newsweek
jcclark at CSUPOMONA.EDU
Fri Apr 2 07:44:49 CST 2004
At 06:01 2004-04-02, John Grehan wrote:
>It is my opinion that the DNA data
>has more potential for being misleading as it seems to be phenetic - for
>all that it may be run through clustering algorithms used by cladists.
"Phenetic" is a type of analysis, not a type of data. And you have yet to
present evidence that the "clustering algotithms" used for morphological
analysis are inappropriate for DNA sequences.
>It's only numbingly difficult if one takes that to be the case. The
>alternative is to consider that overall similarity of DNA sequences really
>have little to do with the phylogenetic sequence.
Perhaps "overall similarity" is not the best measure, but I can't believe
that you are suggesting that evolutionary history leaves traces in the
morphology, but not the genome.
>I have proposed that the
>only sequences that are relevant to such a sequence are those involved with
>the morphological synapomorphies (and if I understand my genetics well
>enough, the DNA representation of each synapomorphy may be scattered in
>different locations on DNA strands as they are brought together through RNA).
So what you are saying is that you choose the evidence that supports your
case, and then only consider the genes that putatively code for it? Nice.
>So far I do not see the DNA being verified as synapomorphies at all.
The procedure is the same as for morphology: root with an appropriate
outgroup. Since you are familiar with the literature, you should be able to
ascertain whether this has happened.
Curtis Clark http://www.csupomona.edu/~jcclark/
Web Coordinator, Cal Poly Pomona +1 909 979 6371
Professor, Biological Sciences +1 909 869 4062
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