Taxacom: Barcodes and species

[Richard Pyle]

Two of the species we described in this paper:
https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdoi.org%2F10.11646%2Fzootaxa.1671.1.2&data=05%7C02%7Ctaxacom%40lists.ku.edu%7C1aef825646ec4c3a312908dc7d87ef47%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C638523270367277387%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C60000%7C%7C%7C&sdata=Nwf84yciWW2DCbrTT%2Fc8M0xzWDjacjE4okEOsSpi8ak%3D&reserved=0 
have multiple instances of identical barcodes (COI) across the type specimens of both species.

They are Chromis abyssus and Chromis circumaurea. You can Google them or look in the paper linked above to see what they look like.  They both have relatively broad (and partially overlapping) distributions. They are not dimorphic (either sexually or over the course of their lifestages) -- their color patterns are consistent throughout their respective ranges.  There has never been a hybrid seen. They differ consistently in morphology as well as color.  Even the lumpiest of lumpers would never consider them as conspecific. And yet... multiple instances of identical DNA barcodes across multiple specimens.

As a side note:  another species described in the same paper -- Chromis degruyi -- has a different juvenile coloration that is part of a convergent color pattern (mimicry?) among juveniles of several species in this genus.  So similar are the colors, that one of the juvenile Paratypes of C. degruyi is, in fact, a juvenile C. alpha.  We didn't realize this until we saw the barcodes.

So... score one point for traditional morphological taxonomy (in the case of C. abyssus and C. circumaurea), and one point for the diagnostic value of DNA barcodes (C. alpha mistaken as C. degruyi) -- all within a single paper!

Aloha,
Rich

P.S. This is also the paper that launched ZooBank, in case anyone is interested...

Richard L. Pyle, PhD
Director of Natural Sciences | Director of EXCORE
Senior Curator of Ichthyology | Database Coordinator of Natural Sciences
Administrator of ZooBank | Mother of Dragons
Bernice Pauahi Bishop Museum
1525 Bernice Street, Honolulu, HI 96817-2704
Office: (808) 848-4115;  Fax: (808) 847-8252
eMail: deepreef at bishopmuseum.org
BishopMuseum.org
Our Mission: Bishop Museum inspires our community and visitors through the exploration and celebration of the extraordinary history, culture, and environment of Hawaiʻi and the Pacific.

> -----Original Message-----
> From: Taxacom <taxacom-bounces at lists.ku.edu> On Behalf Of Mark Costello
> via Taxacom
> Sent: Monday, May 20, 2024 4:09 AM
> To: taxacom at lists.ku.edu
> Subject: Re: Taxacom: Barcodes and species
> 
> Dear John,
> I recall but do not have the paper of some Drosophila species in Hawaii that
> were unmistakably morphologically different species but had the same COI
> gene. Outside insects, I have been reliably told that some other animals taxa
> (Cnidarians?) have little variation in this gene. Some genes vary more and
> some less between species and higher taxa.
> Best regards
> Mark
> 
> -----Original Message-----
> From: Taxacom <taxacom-bounces at lists.ku.edu> On Behalf Of Marko Prous
> via Taxacom
> Sent: Sunday, May 19, 2024 4:30 PM
> To: taxacom at lists.ku.edu
> Subject: Re: Taxacom: Barcodes and species
> 
> Dear John,
> 
> It's possible to have identical barcodes (mitochondrial COI fragment)
> between species, which can be quite common in some groups (sawflies), rare
> in Lepidoptera. You should check also few nuclear genes (or maybe even just
> one might be enough). If these correlate with morphological differences,
> good chance that these are different species despite of identical
> mitochondrial barcodes.
> 
> Occasional hybridization or incomplete lineage sorting can explain this, but if
> nuclear genes clearly separate the species, mitochondrial introgression would
> be more likely explanation (mitochondrial DNA evolves faster than nuclear
> DNA).
> 
> cheers,
> Marko
> 
> On 5/19/24 09:07, John Grehan via Taxacom wrote:
> > As I am pretty ignorant of technical details of species designation
> > and barcode identity, I would be grateful for any feedback on whether
> > it is possible for two 'species' to have identical 'barcodes' (never
> > liked that label with its essentialist connotations).
> >
> > I have a colleague who has collected some ghost moths from the same
> > date and location. There are two morphs - for simplicity 'white spot'
> > and 'plain'. Dissections of genitalia also show differences, with the
> > white spot and plain each showing consistent differences, although
> > only 2 specimens for white spot and 3 for plain. Even with this small
> > sample I am kind of intrigued that the external difference matches the
> > internal difference.
> >
> > The genitalic differences are prominent enough that I would normally
> > view them as indicative of species difference. Perhaps there is a
> > single polymorphic species, but correlated external and internal
> > differences were a bit of a surprise. Any comments or enlightenment
> > would
> be very welcome.
> >
> > Cheers, John
> >
> 
> _______________________________________________
> Taxacom Mailing List
> 
> Send Taxacom mailing list submissions to: taxacom at lists.ku.edu For list
> information; to subscribe or unsubscribe, visit:
> https://lists.ku.edu/listinfo/taxacom
> You can reach the person managing the list at: taxacom-owner at lists.ku.edu
> 
> Nurturing nuance while assailing ambiguity for about 37 years, 1987-2024.
> 
> 
> 
> _______________________________________________
> Taxacom Mailing List
> 
> Send Taxacom mailing list submissions to: taxacom at lists.ku.edu For list
> information; to subscribe or unsubscribe, visit:
> https://lists.ku.edu/listinfo/taxacom
> You can reach the person managing the list at: taxacom-owner at lists.ku.edu
> 
> Nurturing nuance while assailing ambiguity for about 37 years, 1987-2024.
>