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Cardoso, AL, HLS Carvalho, TCM Benathar, SMG Serrão, CY Nagamachi, JP Pieczarka, LM de Sousa, JS Ready & RCR Noronha, 2016. Integrated cytogenetic and mitochondrial DNA analyses indicate that two different phenotypes of Hypancistrus (L066 and L333) belong to the same species. Zebrafish doi:10.1089/zeb.2015.1213.

Abstract

The diversity of Hypancistrus species in the Xingu River is remarkable and the variation in color morphs represents a real challenge to taxonomists to delimit species boundaries. One of the most recognizable Hypancistrus complexes is the worm-lined species, known in the aquarium trade as King Tiger Plec in English, Hypancistrus “pão” in Portuguese or under the L-numbers L066 and L333 that represent two melanic pigment pattern phenotypes. To assess the identity of these two phenotypes, we described their karyotypes and sequenced part of the mitochondrial cytochrome oxidase I gene (DNA barcode). These fishes have 52 chromosomes (40 meta-submetacentric and 12 subtelo-acrocentric) and a strong heteromorphism in chromosome pair 21 was observed, which does not correlate with the two phenotypes or sex. DNA barcodes separated the samples analyzed from Hypancistrus zebra and other publicly available sequences of Loricariidae showing no divergence between the two phenotypes. The data set indicates that worm-lined Hypancistrus from the Xingu form a single species with clear chromosomal and melanic pigment pattern polymorphisms.

Wow, wonderful study! Do you have a copy? May I get one please?

Never mind, here is a link that worked for me: http://online.liebertpub.com/doi/pdf/10 ... .2015.1213

Thanks, Eric

Got a copy. Contact me if you want one.

Just so I understand what is being stated here- please pardon my unscientific language.

There seems to be one "base" species, H. zebra, and it appears as if it is a "true" species and that the 66 or 333 are basically a "forms" of H. zebra? I also wonder how many of the other wormline Hypancistrus L numbers might fit this same model. What about fish like 236, 173 or many of the other B&W striped plecos?

If I have understood things right, then for me this is not a great surprise. It goes back to what I have noted over the years. Almost from the time they go free swimming until the day they die, there is no mistaking a zebra. Yes, there is variation in the appearance, but it is rarely so great a variation that it calls into to question what species it is.

When I am getting fry from my small assortment of wormline Hypans and find myself pressed for growout space, I am willing to mix species but with one rule. I can mix my zebra fry with my 450s, 236 and both 173 or 173b. I can always sort them out easily. However, I will never mix any two of the non-zebra L numbers as it is too difficult to identify them properly down the road as they grow.

All of my experience is within the aquarium environment rather than the wild. But my hunch has always been that something like what this paper seems to have begun to confirm, that, genetically speaking, a lot of the L numbers here as well as others down the road, may prove to be more closely related than is suggested by their having been assigned different numbers or their exhibiting different patterning.

I have probably misunderstood here, so please correct me where I am wrong. I am really curious about all this and have been for some time. Being a lay person, it is easy for me to interpret the science incorrectly.

I think you misinterpreted it a bit. H. zebra was used as a comparison along with other publicly available DNA barcodes of other loricarids. It does not state that they are the same species as H. zebra. Just that L066 and L333 are the same species. You could extrapolate that other species of wormline Hypancistrus may also be the same species with different phenotypes but that wasn't tested so it wouldn't be fair to say that the data supports that. They may or may not be confirmed as the same species with different phenotypes.

The final sentence in the abstract seems to suggest that more than 66 and 33 are involved. "The data set indicates that worm-lined Hypancistrus from the Xingu form a single species with clear chromosomal and melanic pigment pattern polymorphisms."

236, 173, 399,400, 401 and Hypancistrus sp. `Lower Rio Xingu` would all qualify as wormline species from the Xingu I believe? So are these all the same species?

So then is what is being said then that the zebras and the wormline species have no common ancestor in the past. Is this paper saying there is clear genetic evidence showing that the wormlines plecos in the Xingu are not related to zebras at all but are likely all the same species. I understand they only looked at 66 and 333, but that closing sentence did not state that only these two L numbers were a "single species" it stated the wormlines in the Xingu which would then include the numbers I listed above.

I am now understanding that this paper is saying when it comes to the black and white lined Hypancistrus in the Xingu, there are basically two species, Zebras and everything else. Or am I still not getting it?

Yes, with the possible exception of , which may, or may not, be whatever ends up as.

Jools

What Jools said. But to confirm it you would need to match the DNA of the other wormline L numbers to L66 and L333 samples.

There still might be the possibility that something like L173 is related to H. zebra and may be the result of past hybridization of H. zebra with the wormline species.

Re the 173, I agree with the potential for this to be either a separate species and related to zebras. I wonder if it will get sorted out before the Xingu species suffer from the dam.

And thanks to Narwhal72 and Jools for clearing this up for me and to Silurus for posting the original information.

IMO this is an instance of "lumpers" vs "spliters" and personally feel that if you have a catch location you should keep it pure.

Hi,

thats something important to mention indeed, populations, forms, morphs etc. should always be kept on their own. Even if they are considered to represent the same species (which could be wrong), we shouldn't mix them to keep populations pure.

Concerning the paper, I think its something we have been assuming for long, but now we have the proof expressed in numbers.


cheers, Daniel

TwoTankAmin wrote:So then is what is being said then that the zebras and the wormline species have no common ancestor in the past. Is this paper saying there is clear genetic evidence showing that the wormlines plecos in the Xingu are not related to zebras at all but are likely all the same species. I understand they only looked at 66 and 333, but that closing sentence did not state that only these two L numbers were a "single species" it stated the wormlines in the Xingu which would then include the numbers I listed above.

I am now understanding that this paper is saying when it comes to the black and white lined Hypancistrus in the Xingu, there are basically two species, Zebras and everything else. Or am I still not getting it?

It does not follow that the wormline forms and H. zebra don't share a common ancestor. They are separate species but probably closely related. The final sentence of the abstract extrapolates the evidence from two forms (L66 and L333) to all wormline forms without supporting evidence. You should not accept it as fact, but merely as a suggestion.

I would also add that lack of differentiation in one DNA marker (COI) does not prove these are the same species. Lack of evidence of genetic differences is not the same as evidence of lack of genetic differences. In a group of insects that I used to work on we found very little variation in COI among species that show clear divergence in other, less conserved, markers. The lack of divergence in mitochondrial COI could be due either to recent divergence of species and/or to occasional hybridisation. I'd say that more research is required and best practice would be to avoid mixing the different forms in breeding groups.