Lucy in Newsweek
rjensen at SAINTMARYS.EDU
Thu Apr 1 13:18:25 CST 2004
HJJACOBSON at AOL.COM wrote:You are correct NT never required clock-like mutation rates. In
> didn't require any assumptions about evolution, which why I always found it
> intellectually honest. And NT never claimed its dendrograms were phylogenies because
> it was impossible to tell if the mutation rate in the study group was
> clock-like, unless, of course, you knew the phylogeny of the group before you started.
> My point was that clock-like mutation rates are necessary if overall
> similarity is used to estimate phylogney.
I believe Colless suggested just the opposite - if a phenogram is viewed as an estimate of
phylogeny, there is no need to assume clock-like mutation rates. That might make
interpretation easier, but the methods do not require such uniformity.
Whether or not phenograms should be viewed as phylogenies is a different question
entirely. Most workers in NT freely admitted that the methods were not intentionally
phylogenetic, but they could provide insights to phylogenetic relationships. In fact,
there are many examples in the literature in which phenetic and phylogenetic
classifications yielded quite similar (if not the same) views of relationships.
Richard J. Jensen | tel: 574-284-4674
Department of Biology | fax: 574-284-4716
Saint Mary's College | e-mail: rjensen at saintmarys.edu
Notre Dame, IN 46556 | http://www.saintmarys.edu/~rjensen
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