Lucy in Newsweek

[Curtis Clark]

At 08:07 2004-04-01, HJJACOBSON at AOL.COM wrote:
>Molecular cladograms are
>based on overall similarity of sequences and cladograms are constructed on
>clustering of similarity coefficients.

That's one way of doing it. Maximum parsimony, with outgroup comparison, is
another. A base position is just another four-state character in that sort
of analysis. And then there's maximum likelihood, that many also claim as a
cladistic technique.

>If molecular methods weren't a form of phenetics, why is it necessary for
>sequence substitutions to be clock-like.

It's not.

>The assumption of clock-like change is
>necessary for phenetic studies, not morphological cladistics.

My memory of phenetics (which I learned from Gary Schnell back in the
Pleistocene) contained no assumptions of clock-like rate, which would be
hard to measure with morphology anyway.


--
Curtis Clark                  http://www.csupomona.edu/~jcclark/
Web Coordinator, Cal Poly Pomona                 +1 909 979 6371
Professor, Biological Sciences                   +1 909 869 4062