[Taxacom] Mollusca, major subdivisions
kennethkinman at webtv.net
Sat Mar 14 22:19:25 CDT 2009
Bob and David,
I agree with you both. Many molecular (and morphological)
analyses stop short of looking at a sufficient number of possible trees.
The true tree may not have the most support, and PARTICULARLY if an
inappropriate outgroup is selected.
Trying a variety of outgroups (or combination of outgroups) would
be very beneficial. That is one of the main purposes of my occasional
rants on this topic (2002 and now again in 2009). The assumpton that
the first bilateral metazoan was wormlike continues (from Linnaeus, to
Lankester, to Hyman, to the present day). Vermes has NOT yet been fully
dismantled in my opinion, and wormlike forms are still seen as the
ancestors of both molluscs and arthropods.
And I'd love to do my own in-depth analyses and phylogenetic
challenges, but I don't even have a computer. If I didn't have WebTV, I
wouldn't even have e-mail. I just do what I can with what I have (which
isn't a lot these days). The best I can hope for is that some young
malacologist might be inspired to think "outside the box" and consider
alternative outgroups for Mollusca. And has ANYONE ever even tried a
bivalve outgroup for gastropods??? If I'm right, that could completely
revolutionize the systematics of gastropods.
Bob Mesibov wrote:
Good advice not only for molecular data, of course. Explains why
systematics is a work in progress.
Nevertheless, it's very rare to see the sentiments in Campbell's last
sentence expressed in molecular phylogeny papers. The usual structure
has long been: we took these data, we did this analysis, and here's the
tree with its branch support values. The bit '...and we suspect from
this that clade A is possibly a true evolutionary lineage, but let's
wait to see what other data suggest' is too often missing.
Reminds me a little of Otto Loewy's remark (can't find the exact quote)
that a drug is a substance which when injected into an animal results in
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