>Kirk Fitzhugh wrote: [...] If species are not individuals, but
>rather refer to hypotheses, in the same way that all supraspecific
>taxa are hypotheses, then not considering all available relevant
>evidence in the inference of species leaves those hypotheses suspect.
Geoff Read comment: Isn't an hypothesis by definition an unproven
proposition and therefore 'suspect'? So what has changed? I don't
get particularly concerned that a bar-coder's 'species' could have
different bounds from the taxonomist's external morphology 'species',
and that separately or together, or even with further information
from other tools, that might still not reflect true reality, whatever
that complicated reality is.
Kirk's reply: In my earlier post I consciously used the word
'suspect' rather than what should have been used, which is
'irrational.' I was attempting to avoid using a term that might be
construed as too 'loose' and 'bound to offend,' given reactions to my
previous comments. So, correcting what I said -- when not
considering all available relevant evidence in the inference of any
hypothesis, such an inference will lead to an irrational
conclusion. I have discussed this matter ad nauseam in some of my
recent publications.
Regarding the definition of the term hypothesis, the quality of being
an 'unproven proposition' would then call into question what one
might call a 'proven proposition.' Propositions, proved or not (more
appropriately referred to as confirmed or disconfirmed), are all hypotheses.
So, when one is faced with two or more hypotheses referring to the
same objects, and those hypotheses contradict one another, how is one
to select among the group? If one has not taken into consideration
all relevant evidence in the inference of any of those hypotheses,
then it would be less than rational to prefer one to any other. We
should then be concerned that barcoding promotes the potential
inference of species hypotheses to the exclusion of all relevant
data, for the very fact that science should operate on a basis that
is as rational as possible. The issue is not that one will likely
never know the 'reality' behind their hypotheses, that is beside the
point. As the formation of hypotheses are intended to provide us
with the means to acquire understanding, we compromise that very goal
at the moment we condone the inferences of hypotheses that knowingly
ignore relevant observations. The problem with the enthusiasm for
barcoding is that it actively promotes focusing on one class of
observations to the exclusion of other classes of observations that
are potentially relevant to what is being inferred and what is in
need of being understood by way of our hypotheses.
>Kirk Fitzhugh wrote: [...] So, it is reasonable that we should continue to
>>call into question the rising popularity of barcoding, when sound
>>justification for such an approach is lacking.
>>Geoff Read comment: Well I don't know what the more extravagant
>claims say can be done with the sequences alone. To me it seems just
>another tool, perhaps most appropriately deployed when conventional
>dead-animal morphology is not adequate but there is some evidence
>(like the live colour patterns of the Hirudo) which could indicate
>multiple taxa. To convince me it was an unsound tool in every
>application, you'd have to put up other arguments beyond that it is
>only partial evidence. I already know that and can adjust accordingly.
Kirk's reply: I never claimed that nucleotide sequences are 'an
unsound tool in every application.' What I find unsound is promotion
of the view that the basis for species hypotheses can be reduced to
sequence data when other observations also need to be
considered. This is the danger of using terms with a meaning as
narrow as that for 'barcoding.' It is not a matter of deciding what
data are 'adequate.' That echoes the view that species are entities
that can be caught with the appropriate filter. If species are
explanatory hypotheses, then the link between our observations and
those hypotheses has to pass through our causal questions. It is
those questions that decide how to proceed with inferences to
intraspecific, specific, or phylogenetic hypotheses. Unfortunately,
we seem to have a tendency to forgo considerations of our questions
and prefer to have computers provide us answers. Only problem is,
the answers might not be appropriate to the questions!
Kirk
~~~~~~~~~~~~~~~~~~~~~~~~~~~
J. Kirk Fitzhugh, Ph.D.
Curator of Polychaetes
Invertebrate Zoology Section
Research & Collections Branch
Los Angeles County Museum of Natural History
900 Exposition Blvd
Los Angeles CA 90007
Phone: 213-763-3233
FAX: 213-746-2999
e-mail: kfitzhug from nhm.orghttp://www.nhm.org/research/annelida/staff.htmlhttp://www.nhm.org/research/annelida/index.html
~~~~~~~~~~~~~~~~~~~~~~~~~~~
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