Path: utzoo!attcan!uunet!mailrus!iuvax!bionet!GENETICS.WASHINGTON.EDU!joe
From: joe@GENETICS.WASHINGTON.EDU (Joe Felsenstein)
Newsgroups: bionet.population-bio
Subject: Phylogenetic correlations
Message-ID: <9005301655.AA28781@evolution.genetics.washington.edu>
Date: 30 May 90 16:55:11 GMT
Sender: daemon@genbank.BIO.NET
Lines: 25


In regard to Cheverud, Dow, and Leutenegger's method, I asked them when I
was shown a preprint of their work to explain how it related to other
methods such as my own contrasts method of 1985 (American Naturalist) but
have never seen it adequately explained.

One difficulty with their approach is that when two characters are
evolving in a correlated fashion this should show up in BOTH the
"phylogenetic" and "specific" components.  I believe that their method
assumes that only the latter is to be used to estimate the correlation.

If so then it must lose some power.  I think there may also be a
degrees-of-freedom problem.  If there are four species then my method
forms three contrasts and estimates regressions, correlations, etc from
those.  Theirs seems to make the estimate from four specific components,
which seems to me to be one too many.  Alan's simulations seem to show
reasonable behavior but I would be interested in seeing whether it really
does have the postulated distribution.

I would welcome being corrected on this.
-----
Joe Felsenstein, Dept. of Genetics, Univ. of Washington, Seattle, WA 98195
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