[Taxacom] DNA homologies

[pierre deleporte]

A 10:03 02/10/2006 -0400, John Grehan wrote:

> > - make an exception to this rule when the characters support the group
> > (Homo, Pongo) (e.g.: ischial callosities and enamel thickness)
>
>Are you referring to the fact that I work on the assumption that such
>features are derived for humans and orangutans even though outside Old
>World monkeys and apes ischial callosities are also absent in the other
>primates as well as all other mammals, and that thick enamel occurs in
>two monkeys and some other mammals?

Yes, hence they are not "uniquely derived" as they should be according to 
your own standard ("compatibility" criterion for a priori selection of 
characters)

> > - don't consider the fact that this approach will give different
>results according to the arbitrary depth of the phylogenetic analysis.
>
>I presume you mean that at some level the same character states will
>turn up in other taxa?

Yes they can, you get it

>It's the molecular folks who are showing the molecular data to be
>phenetic by explaining that the alignment process involves an
>optimization for the overall number of substitutions and gaps

not all molecular folks, as you should know better
(at least not the cladistic molecular folks)

>(i.e. each character cannot be evaluated individually because the homology 
>is not
>observable).

this is not true

>One person's logic might be another person's illogic. It all depends on
>the assumptions used.

no, logics is first in rational debates

>Perhaps, perhaps not. I acknowledge your opinion.

I'm not interested in opinions in scientific matters

Pierre

Pierre Deleporte
CNRS UMR 6552 - Station Biologique de Paimpont
F-35380 Paimpont   FRANCE
Téléphone : 02 99 61 81 63
Télécopie : 02 99 61 81 88