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Mickey Rowe (rowe@lepomis.psych.upenn.edu) writes:
>
>...
>
>Although I'm no fan of taxonomic ranks, I think "fundamentally flawed"
>is a bit harsh. It's important to take liberal doses of salt with all
>conclusions based upon such an "artificial" analysis, but aside from
>using other taxonomic ranks (as is being done), I don't see how else
>to approach the subject about which Benton wrote. If your imagination
>is fertile enough to provide alternative strategies, I'd love to see
>them!
Clades, rather than "families" (or members of any other formal rank of
canonical systematics), should be the unit of analysis.
A very good start would be to sort the "families" of conventional taxonomy
into those taxa that are founded on the basis of "magnitude-of-difference"
criteria (recognizable by statements with the general form, "Taxon <a> is
_so different_ from Taxon <b> that I regard it as a <name of category>) from
those that are based on the presence of evolutionary novelties. (A third
category -- the largest? -- might be "we don't know why we call it a family,
but everybody else does....")
Obviously, this process would require (a) participation by specialists in
each group (not all of whom will be willing to inspect closely their
cherished classifications), and (b) phylogenetic hypotheses, to allow an
estimate of which character-states are novelties.
In light of (a) and (b), it is probably unreasonable to expect nice results
any time soon. But the request itself is not unreasonable, and I think it
represents the level of detail and accountability that evolutionary
biologists and paleontologists should demand of their taxonomies.
As for an "alternative strategy," well, there is nothing dishonorable about
admitting that, as now constructed, our data base is not adequate to answer
many questions about diversification and extinction. I would prefer that to
pushing such proxies as "families" beyond the conclusions they can truly
support.
Finally, I think my criticism is fundamental because it goes to the question
of what the Benton study purports to measure and whether the units of
measurement ("families") are good estimators of those phenomena. (Also, I'd
like to have a good answer for my son when he asks, in his innocent way,
"Daddy, how many species are there in a family?" and "Is that the same for
horses as for graptolites?")
Barry Roth barryr@ucmp1.berkeley.edu
Barry Roth barryr@ucmp1.berkeley.edu
Research Associate, Museum of Paleontology
University of California, Berkeley, CA 94117 USA (415) 387-8538
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