Taxacom: Minimalist revision of Mesochorus Gravenhorst, 1829

Buz Wilson buzwilson at gmail.com
Wed Aug 30 13:45:47 CDT 2023


Taxacom, despite the long and sometimes tedious arguments, again serves 
up an interesting paper or issue facing systematists these days. The 
Sharkey et al (2023) inspired me (typically not posting on Taxacom) to 
comment because it shows how small fragments of mtDNA can be useful for 
research but how they also fail to provide "taxonomy". While I enjoyed 
Rod Page's perspective on the matter, I think that, rather than the 
traditional taxonomic practice, the inappropriate use of the taxonomic 
format is the problem. I add to Michael Ivie's post, having followed a 
similar path studying isopod crustaceans.

     1. I agree with Sharkey et al. about the Dasch (1974) key as being 
not useful at all. Any key that uses "or" for two different states for 
the same couplet or undefined adverbs such as "very", as well as using 
difficult and idiosyncratic terminology, is immediately problematic. On 
a planet with literally billions of distinct evolutionary lineages 
(approx= species), a fraction of these included in a key to species in a 
speciose genus is not useful at all (as are single species descriptions 
but that's another issue). Phylogenetic relationships and evolutionary 
patterns of these distinct lineages are more useful to biological science.
     2. The paper found morphologically distinct specimens whose COI 
fragments coded for identical amino acids. Collecting all such 
identified traits into a character list that was coded across all 
specimens studied could provide simple morphological diagnoses for each 
species. Had they done this for their diagnoses, the fieldworker would 
have the ability to sort their specimens into morphospecies more easily. 
Using a COI fragment as a "diagnosis" is not useful except for those who 
have a DNA lab on call.  (We are still a long way away from having a 
"Tricoder".)
     3. mtDNA is useful for distinguishing species but may not be useful 
for describing species. My experience with COI and 16S data from a 
species complex of isopod crustaceans 
<https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.dropbox.com%2Fscl%2Ffi%2Fog569epm9wc4rhwal290m%2FWilson_Humphrey_2020_Eophreatoicus_zt4854_modified_reduced.pdf%3Frlkey%3Dfobygx0r514jq1lut9nm9vmkh%26dl%3D0&data=05%7C01%7Ctaxacom%40lists.ku.edu%7Cacc507b0b20a4351d37808dba98954dd%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C638290180553518003%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=yRIYdNEXXgEGFqAW1x0mNFey4itiyFY%2FnLIRr6s%2B6nk%3D&reserved=0> 
(30+ species; NB: 6.9MB) shows that one can get not only sequences that 
code for the same amino acids but completely identical sequences 
(suggesting that the entire mitochondrion was identical) occur in 
populations of different morphological species. As a result, I am 
uncomfortable with the implication that unique "barcodes" equal unique 
species. Synonyms can occur in DNA "taxonomy", too.
     4. Using the traditional taxonomic description format seems 
unnecessary as was the titular term "Revision". In this point, the aims 
of this scientific enterprise need to be more clearly stated. The paper 
identifies many possibly distinct putative species with detailed 
associated metadata. These data then can be used for ecological 
conservation, evolutionary and other biological inquiries, which should 
be the primary uses. Formal taxonomy is unnecessary since the species 
already have distinct labels associated with useful data.

-- 
George D.F. (Buz) Wilson, Ph.D.
Saugatuck Natural History Laboratory, LLC
website (currently offline): www snhlab com
publications: www researchgate net/profile/George-Wilson-12
email: gdfw at SNHLab com

On 2023-08-30 12:06, Michael A. Ivie via Taxacom wrote:
> While I am not a convert, can we restart this conversation by 
> recognizing we have a problem?  I have discovered (collected and 
> curated) a couple to several thousand new species of beetles and other 
> things in my career, but have managed to describe a couple dozen, and 
> colleagues have added a couple dozen more.  I suspect I am pretty 
> representative of 69 year old systematists with an active field 
> program.  If our goal is to distinguish and share information of the 
> type in this new paper, where they describe "158 new species and host 
> records for 129 species," the approach those who work like I do is 
> simply not going to work.  I will die with thousands of new species, 
> their associations and characteristics still hidden from the people of 
> the tropical countries where I obtained them.  Don't we have to 
> discuss how our current system is failing to achieve our goals?  Isn't 
> Sharkey et al challenging us to face this?  If we don't want to follow 
> their path, don't we have to propose something equally effective 
> rather than just blast them for not doing it our (admittingly failing) 
> way?  I suggest that for ever criticism, an alternative be proposed.
>
> Mike
>



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