On 2/20/07, Bill Whan <[log in to unmask] > wrote:
>
>         A recent discussion on the Frontiers of Identification list is of
> interest:   http://birdingonthe.net/mailinglists/FRID.html   .
>         A technical paper "Comprehensive DNA barcode coverage of North
> American
> birds" has attracted wide attention because it suggests more splits
> might be made in the N. American bird species list.


I, too, have been following this discussion, and I believe that the
spectre of fifteen or
more cryptic species has been accorded more ink than it deserves.

DISCLAIMER:  THE WRITER DISCLAIMS ALL KNOWLEDGE OF GENETICS!  All I know
about genetics I absorbed by osmosis from my step-daughter, who is a genuine
expert on beetle genetics.

With that caveat in place, this is what I have gleaned from reading the
paper.  DNA barcoding is a search for quick and dirty ways of making
identification to species of organisms in the laboratory using clusters of
base pairs on a very limited number of base pairs. The referenced article is
a test of that approach on a well worked-out taxon: namely, North American
birds. The authors were very pleased to report that 94% of all North
American birds could be identified using a string of only 648 base pairs on
a single mitochondrial DNA gene. The comments about the possibility of
cryptic species and the possibility that all the white-headed gulls are
actually one species (which would surprise no one) were merely
specualtions on why the technique failed in some cases.

The following is a quote from the introduction to the full paper:

"DNA barcoding translates
expert taxonomic knowledge of diagnostic morphologic
characters into a widely accessible format, DNA sequences,
enabling more people to identify specimens. In addition to
assigning specimens to known species, DNA barcoding
can speed the discovery of new species, as large sequence
differences in animal mtDNA generally signal species status."


The first sentence says that the taxonomy comes first, then the barcode. The
second sentence says that the barcoding MAY facilitate the discovery of new
species in the future. This is a speculation and it remains to be seen
whether it is very useful.

I have some further ruminations on this topic that I will save for the
Forum.

Cheers,

Bob



--
Robert D Powell
Wilmington, OH, USA
[log in to unmask]

Nulla dies sine linea

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