DNA based lumps, splits and IDs

[Andrew Hobbs <>]

As a molecular genetecist, I would say that relying on 648 bp of 
mitochondrial sequence is about as good at distinguishing species as 
sending out a beginner birder and asking whether they think they 
represent two species.
Cheers

Andrew


Dave Torr wrote:
> Thanks Frank - that is very clear. So the publicity is about as 
> justified as
> (say) a new fig parrot is?
>
> Seriously I have always had doubts (as a non biologist) about some of 
> this
> DNA stuff - I attempted to read one paper and the author seemed to be 
> saying
> that if the difference in the small part of the DNA he had studied was 
> more
> than "x" % then he would declare the beasts to be separate species. The
> choice of "x" seemed totally arbitrary.
>
> Still - I guess as long as taxonomists can generate new ways of 
> looking at
> the world we will never be short of the need to buy new bird books and
> update our "life lists"
>
>
>
> On 23/02/07, Frank Rheindt <> wrote:
> > David (and others),
> >
> > trying to keep it short:
> >
> > 1.) These DNA barcode people are just looking at one single gene (COI),
> > which happens to be one out of three dozen genes on the mitochondrion (a
> > tiny cell organelle). In the nucleus of each cell, there are millions 
> > and
> > millions more genes, many of which are responsible for the appearance of
> > an
> > organism. So it all depends on what you really want to do: If you were
> > looking at a gene that codes for the colour of a duck's wing 
> > speculum, you
> > bet there would be huge differences between Blue-winged and Cinnamon 
> > Teal.
> > However, phylogeneticists try to look at neutral genes that don't have
> > anything to do with what an organism looks like, to avoid circularity.
> >
> > 2.) Barcoding is a nice tool to detect "suspects" for splitting/lumping,
> > but
> > in most cases more phylogenetic work will be necessary to corroborate 
> > the
> > split/lump. For example, let's take the case of those "species with
> > identical DNA": First of all, never say they have identical DNA, but say
> > something along the lines of "...they have an identical sequence in 
> > their
> > COI gene..." (which is less than a millionth of their total DNA).
> > Secondly,
> > the reason for having an identical COI sequence could be manifold, and
> > could
> > involve things such as ancient hybridization events (during which one
> > species' COI gene "invaded" that of the other) - this is called
> > mitochondrial introgression and is fairly common in birds. So those
> > species
> > can still be viable and valid species despite that finding! (A similar
> > case
> > in Australian birds involves White-browed and Masked Woodswallows, which
> > have identical mitochondrial DNA).
> >
> > Bottomline: DNA barcoding is a nice tool to whet our appetites, but in
> > each
> > case, a split or lump requires subsequent follow-up studies to 
> > corroborate
> > the case.
> >
> > Cheers
> > Frank
> >
> >
> >
> > >From: "Dave Torr" <>
> > >To: "L&L Knight" <>
> > >CC: Birding Aus <>
> > >Subject: Re: [Birding-Aus] DNA based lumps, splits and IDs
> > >Date: Fri, 23 Feb 2007 15:30:04 +1100
> > >
> > >Maybe I'm missing something (and I'm no expert on DNA!). The 
> > reference on
> > >"splits" shows a number of what I have always thought of as "good"
> > species
> > >anyway, with no indication of what they have been split from (or 
> > what has
> > >been split from them).
> > >
> > >And the DNA lumps shows Blue-winged Teal and Cinnamon Teal to be 100%
> > >similar - yet visually at least they are very different...... Since 
> > as a
> > >"layman" I assumed DNA controlled the appearance of an animal how can
> > this
> > >be the case?
> > >
> > >Please excuse the ignorance but I would love someone to explain in 
> > simple
> > >terms.....
> > >
> > ><>
> > >>
> > >>
> > >>< DNA splits >
> > >>
> > >>http://www.eurekalert.org/multimedia/pub/3183.php?from=90533
> > >>
> > >>Unique DNA barcodes for provisional new bird species were obtained 
> > from
> > >>these look-alike specimens.
> > >>
> > >>
> > >>< DNA lumps>
> > >>
> > >>http://www.eurekalert.org/multimedia/pub/3185.php?from=90533
> > >>
> > >>These groups of bird species were shown to have virtually identical 
> > DNA.
> > >>
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