Silphidae on Tree of Life

Richard.Zander at MOBOT.ORG Richard.Zander at MOBOT.ORG
Fri Feb 11 09:32:57 CST 2005


As I understand it, Steve, certain genes and other molecular groups have
particular rates of mutation. Some genes are very variable and are useful at
lower taxonomic levels, and others are not, and are used to analyze
phylogenetic relationships at higher levels.

The sampling has not been great, but from what has been done, particular
genes have the same sequence, for, say, all samples of a species. So single
samples are commonly used as representative of particular taxa. This is not
great but because of the observed regularity, funds and time have been
focused on large scale analyses with exemplar taxa. If you have the funds
and time to determine more exactly how well single samples represent entire
taxa, there are a whole lot of us out here who are interested.

Yes, molecular study is informed by morphological study. The fact that the
results of molecular study and morphological study generally concur is no
longer amazing, so molecular study is now expected (by me, anyway) to solve
knotty problems and resolve contradictions, disappointing so far. In spite
of the paper by Lee in Taxon 53(4): 1019-1022, 2005, morphological traits
are too few to be impressive statistically, and this is one of the reasons
molecularists tend to discount morphological studies when they contradict
well-supported molecular results. If you have the funds and time to
investigate how to interpret morphological characters such that cladograms
based on morphology generate high bootstrap or posterior probabilities,
there are a whole lot of us out here who are interested.

Oh, the Lee paper . . . the argument is that morphological data already has
all non-relevant data deleted, so there are as many traits (about) useful
for phylogenetic analysis as in molecular studies. True, but probably not a
relevant argument, since the number of morphological traits needed to
uniquely define 10 taxa is 11. The branch length is not 10.

Convergence afflicts morphology, as it does, doubtless, exons. This hasn't
been dealt with well, and if you have the funds and time . . . . . . etc.

______________________
Richard H. Zander
Bryology Group
Missouri Botanical Garden
PO Box 299
St. Louis, MO 63166-0299
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Voice: 314-577-5180
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-----Original Message-----
From: Steve Manning [mailto:sdmanning at ASUB.EDU]
Sent: Thursday, February 10, 2005 5:14 PM
To: TAXACOM at LISTSERV.NHM.KU.EDU
Subject: Re: [TAXACOM] Silphidae on Tree of Life


Derek,

I was surprised by the latter part of this.  Are you saying that the
samples taken for molecular phylogenies are not from specimens identified
as to geographic location from which the specimen was taken?  Presumably
the alpha taxonomy could have been done in the past rather than along with
the sampling (?)  I would hope that molecular phylogenies are based on a
reasonably thorough sampling of the variation, including geographic
localities, within each taxon(?)

In other words I guess what I am really trying to say is that alpha
taxonomy results in geographic distribution information only after the
info. is gathered and the classification is made, and I don't see why
molecular phylogenies should be fundamentally different in this regard.  In
either case, incomplete geographic info. seems better than none at all,
assuming it is relatively easy to upgrade as new info. is brought to your
attention.

Are molecular phylogenies accepted for publication in the absence of
reference to voucher specimens, including localities, from which the
molecules are extracted?

Steve




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