One can't talk about clusters in that way for mitochondrial sequences
which are inherited from the female parent only and do not undergo
recombination. At least in any meaningful way. There are any number of
reasons they could get clusters in different groups which have nothing
to do with possibility of different species.
Cheers
Andrew
Wim Vader wrote:
I have downloaded and read the paper involved (which to me seems a
prerequisite for having strong opinions on the matter), and nowhere do the
authors 'make splits and lumps'! What they do, is to draw attention to the fact
that in most cases the very small fraction of mitochondrial DNA that they
examine in the bar-coding project shows clearcut interspecific differences and
small intraspecific differences. There are a number of exceptions to this
general rule, though, and as happens so often, these have drawn almost all the
attention away from the main message, which is: bar-coding can be of great help
in rapidly identifying bird species from biological material.
These exceptions are of two types: in a number of species there ARE clear
INTRAspecific differences, and one gets two clusters instead of one cluster.
The authors remark that these cases may well involve cryptic species, and
indeed in many of them morphological and biological studies already had
intimated that these species were not homogeneous. together, these data may
well utlimately lead to further splitting in these cases.
In the other type of exception the ARE NO clearcut INTERspecific differences in
this particular part of the DNA. (NB, It is of course quite wrong then to jump
to the conclusions , as several mailers have done, that ' the DNA is equal':
there may be lots of differences in other parts!) Also here the authors of the
present article are commendably careful; they discuss several possible reasons
for the great similarity of the DNA fragmnants involved, and urge further
studies.
It will therefore definitely be some time, at best, before we can start adding
and subtracting species from our life lists!
I am a classical taxonomist of crustaceans, not evenbirds, so my words do not
carry particularly much weight
Wim Vader, Tromsø Museum
9037 Tromsø, Norway
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