DNA and all that

Ken Kinman kinman at HOTMAIL.COM
Thu Feb 6 02:29:08 CST 2003


Don,
      The text of "The Disappearance" appears to be available online at the
following URL address:
    http://biology.uoregon.edu/classes/Bi442s02/protected/disappearance.html


*****************************************
>From: Don.Colless at CSIRO.AU
>Reply-To: Don.Colless at CSIRO.AU
>To: TAXACOM at USOBI.ORG
>Subject: DNA and all that
>Date: Thu, 6 Feb 2003 13:05:05 +1100
>
>This thread must be thinning fast, but h'with my 2 cents' worth. The group
>of Diptera on which I currently work has about 35 species in 2 (arbitrary!)
>genera, and I have on average about 30-40 specimens per species. It would
>be
>great to have DNA profiles of the several species. It would, especially,
>help associate males and females, which I can't at present do for some
>species. It could also provide a competing estimate of phylogeny, for
>comparison with a morphological one, with possible improvements in both (I
>join Richard Zander in his distrust of trees!). But, as several folk have
>pointed out, in reality the work involved would be impossibly demanding of
>time and money.
>
>  Occasionally we see the magic word "sampling" injected into the
>discussion,
>as a way to reduce the load - but samples of what? Of sequences from
>genomes, perhaps; but the possible traps are obvious. Or of specimens from
>taxa - which could obviously help enormously IFF we already had the taxa
>delineated and suitable specimens in the freezer. The fallacy here is
>obvious enough: the "DNA taxonomy" is supposed to provide the delineated
>taxa!. in fact, what has been suggested (in the TREE article at least)
>seems
>to be something along the lines of current bacterial "shotgun" taxonomy -
>of
>genomes, not species.
>
>A well-trained "taxonomic eye" is a tool beyond price, in that it can run
>over a couple of hundred specimens and sort them quite rapidly and pretty
>accurately into groups, which can then be attacked individually and quite
>efficiently. To "sample' the mass of specimens would no doubt pick up the
>common species, but very likely miss the less common.
>
>I join many of my colleagues in the fear that the DNA bandwagon will roll
>(financially) over traditional taxonomy; but we can just hope that good
>sense will eventually prevail - especially when folk who need the services
>of a REAL taxonomist can't find one! A propos, there was a wonderful
>article
>in Taxon many years ago - entitled, I think "The Disappearance" (my copy
>was
>lent or stolen). It's worth hunting for.


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