Australopithecus and orangutans

[Michael Bayly]

Herb,

I don't follow your logic here...

"A"s and "T"s are not characters they are character states (at a given
position, = character, in the sequence alignment).  

By the same logic would you not accept the two following morphological
characters in analysis (because they have states with the same names)?:
leaf margins: hairy (0)/ glabrous (1)
carpel apex: hairy (0)/ glabrous (1)

Obviously there might be cases where you might think states in these
characters are linked (not independent), but often they would not be, and
you could test this by congruence with other characters.

 
Mike

----------------
Dr Michael Bayly
Research Scientist in Plant Biosystematics
Museum of New Zealand Te Papa Tongarewa
PO Box 467 
Wellington, New Zealand
Ph: +644 381 7262
Fax: +644 381 7070



-----Original Message-----
From: Herbert R. Jacobson [mailto:HJJACOBSON at AOL.COM]
Sent: Thursday, 15 May 2003 8:53 a.m.
To: TAXACOM at USOBI.ORG
Subject: Re: Australopithecus and orangutans


Jason,

What kind of argument is: " if molecular characters can never be used for
evolutionary analysis, then why do they so frequently give phylogenies
that are congruent with "real cladistic analyses"? "

For the same reason a stopped clock is correct twice a day is the answer to 
that argument. What do you mean by frequent? Since molecular phylogenies for

any group are proposed more frequently than character phylogenies, it
doesn't 
surprise me that agreements occur.

As for As and Ts being the same as morphological characters, I can't
disagree 
more. In order to obtain a fully resolved cladogram with morphological 
characters, it's necessary to have at least as many characters as taxa.
Using 
As and Ts  would limit the cladogram to not more than 4 or 5 taxa if it's to

be fully resolved. Since this isn't the case As and Ts can't be the same or 
equivalent to morphological character.

If you meant sequences then I think the problem is worse because most 
molecular studies use only one sequence, unless of course the whack  up the 
sequence in to subsequences by some a priori rule.

Herb
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