EBJD

[captainahab]

I have just recently returned to this amazing hobby, after about 10 yrs hiatus. 30 yrs exp prior to that, but wow, it seems I've missed a lot!

Case in point; Electric Blue Jack Dempsey.

My background is in genetics with extensive exp with hundreds of species.

But the EBJD has me stumped. I want to make use of this blue gene, but need to understand it first, but all that I read is antecdotal nonsense. Hopefully someone knows of a scientific study or has the knowledge to answer this;

If the gene is a simple recessive, then 100% of offspring would be blue and as healthy as parents.

If the gene is a simple dominant, then percentages would be 25, 50 or 100 depending on parental genotype. But still no reason to get unhealthy or dead babies.

If the gene is a duo-dominant, then blue progeny percentages would be 25% non blue, 50% blue and 25% something else; possible dead if semi lethal. In the case of semi-lethal, the percentages of live babies would be misleading because the numbers would seem to be 1:2, or 2/3 blue (failing to take into account the 25% dead). Still, in this scenario, the 50% blues should be healthy and normal.

If the color is actually polygenetic, then the percentages of the F-2 and backcrosses would be FAR lower than being claimed. Also, would make the likelyhood of appearing in the wild extremely low; and supposedly they do.

I can think of no mechanical reason that could account for the supposed absolute failure of EBJD x EBJD matings to produce viable offspring. The idea of the blue lines being too inbred makes sense, for about 2 seconds. If that were true, all of these extreme versions of outcrossing to produce blues would fix that problem very quickly. That's not the problem.

Ok!!! What's the deal?

 

[jakeca77]

All that I have read is anecdotal as well. I am also curious about why 2 EBJDs cannot be bred to produce more EBJDs. Is it because 2 lethal genes are paired up and no viable offspring is produced? There is also the method of using an EBJD male X with a BG female that I wonder about. Why couldn't you mate a BG male with a EBJD female and get the same effect or is that just standard practice? Are EBJD females ever produced and are they fertile? Also, the mating of an EBJD male X BG female does not result in 100% EBJD offspring (from what I have read). There are so many factors that you have laid out that could be at play. I wonder if the EBJD variant might be tied to the sex chromosomes (X or Y)- like what is seen in Hemophilia? I have a feeling though, that it is something that is as complicated as eye color in humans. I have also read that somebody had a DNA analysis done on a EBJD to determine whether or not it was a hybrid and the answer was no. How would they know this though? Last I checked the genome for Rocio octofasciata has not yet been sequenced? It is not that easy to determine if an organism is indeed a hybrid by looking at the genome of only one organism.

 

[captainahab]

Yea, I forgot to mention the sex-linked option. Don't think so because with so many outcrosses going on, it would become VERY obvious if it was sex linked. There are other possibilities, but highly unlikely. Everyone is quoting this "hybridity study", but I have not been able to find it. My gut feeling is that very few have actually tried the homozygous cross, and are only passing on heresay.

 

[muffywrx]

I actually am unsure I have seen evidence of two EBJD maturing and mating together successfully... the eggs normally dont hatch or the fry die after the first 10 days.

I think the genetics are too weak to produce anything that can survive. When crossed with a regular JD or blue gene JD, the stronger genetics are able to carry the fry to health.


EDIT: Have read many accounts of people attempting this ... and none have been successful.

 

[captainahab]

Don't mean to raise fur (fins!) but the term "genes are too weak" has no meaning whatsoever. In order to figure this out, we have to eliminate the witchcraft and study what is really happening.

I too, have read many accounts of failed attempts. I can also tell stories for hours of failed attempts of all sorts of perfectly normal, healthy, wild type fishes. Doesn't mean it can't be done, means I failed.

There are 2 causes that people refer to as "weak genes". 1st and most common is animals that are the result of intense inbreeding that reduces the heterozyosity which weakens the animal. 2nd and usually also associated with inbreeding is the alignment of many, normally insignificant, deleterious recessive genes. Both of these problems are alieved with outcrossing.

A genetic value cannot be weakened or strengthed. It is what it is. IMO, mutations happen on loci that are prone to being relatively more mutable, but they do not switch back and forth.

 

[muffywrx]

No fur raised. I don't understand it either. Wish someone knew why, but there is an entire forum dedicated to blue jack dempseys and no one there knows either, though many have had fry hatch and live for less than 10 days, even in good conditions. Suggestions have been made that perhaps they need a special type of care that no one has figured out yet. Another suggestion is like you have said, due to inbreeding, but haven't seen accounts of non-inbreeding being successful either.

I know that some claim that the blue gene is a mutation, and is that not a cause for weak genetics, such as celiac disease in humans (though we have found a way to live with this disease) ... if that is the case, there should be a way to keep them alive, but maybe the mutation is only viable when offspring from a regular jd and when two ebjd cross, the mutation x mutation results in something that can't survive? Just food for thought. I'm no expert. But say a blue gene dempsey has a mutation that causes internal problems, causing them to be delicate when young. If it breeds with another blue gene dempsey, perhaps the internal problems are escalated to a point of insurvivability?

 

[Andrewtfw]

Having no background in or solid understanding of genetics, I do have a strong interest in EBJD. As a result, I find this discussion quite interesting and am thankful for the education. Though I currently have 14 EBJD ranging from juvenile to adult, I have had no luck (possibly due to space) in breeding any EBJD.

 

[Bully Fish]

I had typed out a fairly long reply earlier today and just stopped and deleted it. Basically everyone who got really involved in breeding ebjd noticed the quality of their spawns decreasing as time progressed and gave up. Seriously, look at the pictures by tommy lay and others from the early 2000's. Very nice fish. Despite the effort and thought put into breeding these fish (maximum outcross with regular dempsey, getting their blues from different sources, and avoiding inbreeding at all cost) the results were always the same. I would think if the problems these fish have would be less of an issue with so much effort put into "repairing" the ebjd bloodline. I really don't know what to think about the genetic question hanging over ebjd bit I love them and will carry on my breeding project doing what I think will give me the best results.

 

[mbeezy618]

wow this is a very interesting subject...thanks for a better understanding on EBJD...

 

[jakeca77]

It goes without saying that they are a beautiful bunch of fish.

If people have been successful at spawning EBJD pairs but the fry did not survive past 10 days then I would think that the offspring must be homozygous for a lethal trait. It could be something similar to phenylketonuria (PKU) or any of the many other genetic disorders in humans that would kill or cause developmental defects in newborns without proper treatment. The offspring may not be producing an enzyme or protein correctly, causing them to die. We will never know unless somebody sequences and does a thorough study of the regular JD genome and then compares it to that of an EBJD. Somebody could do a necropsy on the dead fry to determine why they died... If that is even possible on such a tiny undeveloped specimen?? Anybody know a fish pathologist?

In regards to a mutation being a cause for "weak genetics"..... . You have to understand that mutations are not always a bad thing. They can be a good thing, it just depends. Mutations could lead to death or it can lead to the evolution of a new species.

Regarding the hybrid study - if it was done. I wouldn't trust any kind of genetic study that was performed to determine whether or not the fish was a hybrid that hasn't been undertaken within the last couple of years. Case in point, for years, the experts were saying that humans had not hybridized with neanderthals. There are now studies out that say that we are. So as the technology impoves and we learn more, the information can change. The fish don't look like hybrids to me but who knows. I am no expert. The fish breeder did not share his notes or work on how the strain was developed. That in itself might make some ask if it is a hybrid. Most breeders keep good notes on what they are doing, these notes would answer a lot of questions. If it wasn't a hybrid then why the secrecy? The EBJD is supposed to be naturally ocurring but how many hobbyists that are just breeding 2 regular JDs together are lucky enough to find one EBJD? I can understand why a breeder that is culling his fish might discard them, but the home hobbyist that is just trying to raise some fish for fun? Somebody should see them? The determination of hybridization by using genetic testing is still going to be difficult since we have no idea what the other progenitors could be in this strain.