Fwd: Re: [TAXACOM] genetic vs morphological trace of phylogeny

[John Grehan]

At 08:57 PM 4/8/2004 +0200, pierre deleporte wrote:

>Not agreed. You discard molecules and shouldn't. Why not apply your
>principles to yourself?

I anticipated that someone might make this inference. However, it is not
correct. My view is that molecular characters are ambiguous and there are
several issues contributing to that ambiguity such as the question of
phenetics and also character alignment for homology.

I take the view that a molecular phylogeny is not necessarily correct or
better than a morphological phylogeny. I see the potential for the two to
either agree or to come into conflict, in the latter case one has a
research anomaly. In the orangutan case I find the morphological
synapomorphies of humans and orangutans to be more problematic if the
molecular tree were to be considered true than the other way around.
Conversely, others see the opposite.

Combining the data does not solve this anomaly - rather it is obscured. So
I may make a choice in favor of one over the other in this specific case
(as a personal choice, not by kind of universal criterion since there is
none). This is not to say that molecular trees may not be 'better' or more
predictive than morphology in other situations. Its just that there is no
recipe for deciding. Each might be argued case by case. This is different
from molecular views that take a universal position that only DNA sequence
data is reliable when it comes to a choice between DNA sequence data and
morphology.

John Grehan


Dr. John Grehan
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