Lucy in Newsweek

Thu Apr 1 13:20:53 CST 2004

In a message dated 4/1/2004 9:58:43 AM Pacific Standard Time,
rjensen at SAINTMARYS.EDU writes:

> Some years ago, Don Colless suggested that under certain circumstances
> phenograms were quite likely to be good estimates of phylogeny; he noted
> that
> rates of evolution need not be "clock-like" but that differences in rates
> between nodes in a clade should not vary appreciably (in fact, if I recall
> correctly correctly, he also noted that if the rates were uniform, the
> lengths
> internodes of the phenogram could be interpreted as units of time).

I'm not going to argue about the difference between clock-like and "not vary
appreciably," but what you say is the point I was trying to make: if mutation
rates do "not vary appreciably," phenograms are reasonable estimates of
phylogny. From this I drew the conclusion that molecular cladistic must be a form of
phenetics because they required clock-like substitution rates. But Curtis
tells me that is not a necessary requirement.

Herb Jacobson

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