[Taxacom] very nice opinion article in today's Zootaxa

Michael A. Ivie mivie at montana.edu
Fri Sep 16 18:39:16 CDT 2011


Could we have the rule that  people who have not read the papers under
discussion should not have opinions about those papers?  Geez!  It seems
to me that only Jim and John have any basis for what they are saying.

Mike Ivie


> Not to argue for using only one sample to stand for a species, or only one
> DNA barcode, as I agree with you that it is a bad idea.
>
> But if people would bother to look carefully at the original papers, they
> are based on LOTS of molecular samples from each species.  It is the
> CONSISTENCY of the molecular or morphological differences that is
> critical, not how major the differences are. In this case the molecular
> and morphological differences are consistent across many samples within
> putative species and do indeed support one another.
>
> Most species descriptions based on morphology (probably 95% + of all
> species descriptions?) do not have any convincing analysis associated with
> them. We are in the habit of trusting the experts in this case rather than
> requiring strong evidence.  Most of the time this works really well, I'd
> say.
>
> Jim
>
>
>
>
>> Exactly. The question is whether a one specimen sample will suffice for
>> a
>> species description. YES, that the specimen is connected to a systematic
>> morphological study of many specimens is importanat, but it is not
>> support
>> or refutation of the morphological conclusions. Only if the molecular
>> analysis can stand on its own can it either support or refute another
>> concept.
>>
>> _______________________
>> Richard H. Zander
>> Missouri Botanical Garden
>> PO Box 299
>> St. Louis, MO 63166 U.S.A.
>> richard.zander at mobot.org
>>
>>
>> ________________________________
>>
>> From: taxacom-bounces at mailman.nhm.ku.edu on behalf of Doug Yanega
>> Sent: Thu 9/15/2011 5:05 PM
>> To: TAXACOM at MAILMAN.NHM.KU.EDU
>> Subject: Re: [Taxacom] very nice opinion article in today's Zootaxa
>>
>>
>>
>> Among the references that John Shuey listed, I noted the following
>> one, which I had not seen before:
>>
>>>Burns, J. M., D. H. Janzen, M. Hajibabaei, W. Hallwachs and P. D. N.
>>>Hebert 2007. DNA barcodes of closely related (but morphologically
>>>and ecologically distinct) species of skipper butterflies
>>>(Hesperiidae) can differ by only one to three nucleotides. Journal
>>>of the Lepidopterists' Society, 61:138-153.
>>
>> If that title is taken at face value, would this not invalidate the
>> premise that patterns of sequence divergences on a tree can be used
>> to recognize species boundaries? The implication of the parenthetical
>> phrase above is that morphology and ecology MUST be given primary
>> credence, which runs contrary to what many seem to be preaching
>> and/or practicing; that is, if it is admitted that barcodes alone are
>> insufficient for the task of species delimitation, then what is the
>> justification for studying and promoting barcodes alone? If good
>> species can differ by one base pair, then (a) how could one *ever*
>> know whether a single base pair difference is or is not indicative of
>> a species-level difference without morphology to back it up, and (b)
>> can we not therefore assume that there must be many cases where
>> species have ZERO base pair differences (i.e., that barcodes are not
>> unique, as claimed)? And, given that subspecies are typically
>> morphologically distinct, then, by extension, barcodes could never
>> help distinguish species from subspecies - only ecology (i.e.,
>> breeding experiments, etc.) would be definitive - in which case
>> barcoding is of rather more limited utility than its proponents
>> generally claim; it would seem to come into play only if one has two
>> otherwise very similar sets of organisms whose barcodes are
>> *dramatically different*. That's certainly potentially useful in some
>> contexts, but far from a solution to the "taxonomic impediment" as
>> was initially claimed by Hebert, and only serves to enhance my
>> already skeptical view of the barcoding enterprise.
>>
>> Or am I missing something here?
>> --
>>
>> Doug Yanega        Dept. of Entomology         Entomology Research
>> Museum
>> Univ. of California, Riverside, CA 92521-0314        skype: dyanega
>> phone: (951) 827-4315 (standard disclaimer: opinions are mine, not
>> UCR's)
>>               http://cache.ucr.edu/~heraty/yanega.html
>>    "There are some enterprises in which a careful disorderliness
>>          is the true method" - Herman Melville, Moby Dick, Chap. 82
>>
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>
>
> --
> James B. Whitfield
> Department of Entomology
> 320 Morrill Hall
> 505 S. Goodwin Avenue
> University of Illinois
> Urbana, IL 61801
> http://www.life.illinois.edu/whitfield
>
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-- 
Michael A. Ivie, Ph.D., F.R.E.S.
Montana Entomology Collection
Marsh Labs, Room 50
1901 S. 19th Ave
Montana State University
Bozeman, MT 59717-3020
USA

(406) 994-4610 (voice)
(406) 994-6029 (FAX)
mivie at montana.edu






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