genetic vs morphological trace of phylogeny

pierre deleporte pierre.deleporte at UNIV-RENNES1.FR
Tue Apr 13 13:07:13 CDT 2004

A 18:05 12/04/2004 -0400, Herb Jacobson wrote:

>Since DNA is cladistic,

more precisely: can be analysed cladistically (and phenetically, and any 
way you like). For "cladistic" never qualified characters (contra John 
Grehan's obstinate statements).

>I was also in error about the need for sequences to
>have clock-like or regular mutation rates. Like morphological studies, sister
>clades can diverge at different rates. Mutation rates are, as I think Pierre
>said, a measure of phenetic differences between clades. Here the phenetic
>information is added to a cladogram and not used to make the it. This 
>would also
>provide a test for sequences thought to have regular mutation rates. Again I
>think Pierre said that, but I hate to put words in his mouth.

No problem, you get the essential of it.

>However, in some studies phenetic differences are used as a proxy for time
>and there, I would assume, the sequences used would have to have regular
>mutation rates. In these kinds of if sister clades had different mutation 
>rates it
>would mean that they split at the same time but arrived at the present at
>different times.

Or at different "evolutionary speeds". Confrounting phenogram and cladogram 
is effectively a way to check after possible regularity of evolution.

>Herb Jacobson

You're certainly not a person targeted as refusing to learn !
I'm certain I also learn a lot on taxacom, including about Pongo's morphology.
But logics is logics...

Pierre Deleporte
CNRS UMR 6552 - Station Biologique de Paimpont
F-35380 Paimpont   FRANCE
Téléphone : 02 99 61 81 66
Télécopie : 02 99 61 81 88

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