In regards to the OPs original question
A typical brood of regular Dempseys that commonly survive (in captivity) to sellable size is about 10 times the amount Blue Dempseys that survive to sellable size
　
　
japes;3933489; said:
What actual proof do you have of this though?
　
As Sarah mentioned, they breed out following typical Mendelian Genetics. The results of hybridization do not follow this method, natural occurring recessive alleles do
This is proof in and of itself
　
Jeff Rapps financed the first round of genetic testing. The test searched the mothers lineage for anything other than R. octofasciatus. None was found
　
A Hobbyist named Cole won the attention of a Professor of a University who did a newer form of testing and also found nothing but R. octofasciatus
Details of both can be found at wwwallthingsdempsey.com
　
japes;3932843; said:
why has this gene not spread thoroughly through wild populations?
　
It is well known that gene mutations happen and happen fairly commonly. There are several theories of why, but no one truly knows.
　
It is likely that at a particular location, Blue Gene or heterogeneous for blue allele R. octofasciatus exist commonly. But the location of the original FO Blue Gene (or het blue) was not documented and is unknown.
　
But it is exceptionally unlikely that this mutation would move beyond the original location, since if a Blue Gene or het blue individual migrated from the original location and spawned with a standard Dempsey from another location, the offspring would all be standard Dempseys.
This is how evolution works. Recessive qualities that are advantageous make individuals with them more likely to breed thus making them more common and spread throughout a population/species
but recessive alleles that are not advantageous prevent individuals exhibiting them from spawning and individuals exhibiting it recessively or heterogeneously to dwindle
japes;3932681; said:
Inbreeding is the usual excuse given for the high mortality rate, overall weakness, and common occurrence of deformities within EBJD's, but with Blue Gene JD's being a wild, naturally recessive gene, wouldn't that bring in the possibility of F1/F2 (I'll leave F0 out of that) EBJD's.
　
Since the originating location of the F0 Blue Gene or het blue Dempseys is unknown
and since Blue Gene or het blue Dempseys have no visual differences from the normal (wild type) Dempseys
removing F0 Dempseys from the wild is exceptionally difficult. Add to that the region Dempseys are native to (Yucatan) is exceptionally difficult to collect fish from
its just not going to happen
　
Creating a breeding program using FO standard Dempseys bred with Blue Dempseys would be a marvelous idea and many of us have put considerable efforts into trying this. But again, since true F0 Dempseys are exceptionally hard to come by, it has yet to happen.
　
japes;3933489; said:
- Why the genetic weaknesses from what is essentially a recessive colour gene, when the same is not present in many albino/leucistic/xanthic/piebald variants?
　
It is not uncommon for two different recessive alleles to pair up so that even though they are unrelated, they are passed together.
　
japes;3933489; said:
- Why have EBJD keepers, who I believe the onus should be on to provide proof they are a natural species, not funded and performed DNA testing? The same loop of "You have no proof it's not a hybrid > You can't prove it is a hybrid" continues to run on. They certainly make enough money from the fish themselves.
　
As mentioned above, its been done. 8 years or so ago when Jeff had it done he openly shared the results
3 years or so ago when Cole had it done he openly shared the results (including in a thread here).
　
　
Sarah88;3933542; said:
...because like both me and japes have said it is all conjecture and there is no actual scientific study saying anything either way so until that is done this will be a continuous argument...
　
There has been DNA sequencing done
and elsewhere on the site linked previously details of it can be found
　
Also, deductive reasoning is much more than speculation
　
When two species hybridize, the offspring display a varying combination of qualities of both parent species
this is not what happens with Blue Dempseys
　
When a recessive allele is passed via Mendelian Genetics, which is a very well known and thoroughly understood genetic path, Punnet squares can be used to predict the appearance and genetics of the offspring. This is the case with Blue Dempseys
　
　
This is a very interesting topic (to me at elast) but has been thoroughly covered numerous times.
　
The reptile hobby (especially Corn Snakes) have applied a very respectable understanding of recessive alleles, Mendelian genetics and color morphs. Spending some time reading their explanations or even reading the Wikipedia pages on those three phrases will make understanding Blue Dempseys much easier.
I hope this doesn't sound argumentative or challenging... I'm just sharing what I've learned :-D
and their ratios are wrong, in the punnet square its correct for when crossing a Bb x Bb but in the bottom when its talking about breeding a bgjd to an ebjd and its says you will get at best 15-20%, that number would be for if you crossed 2 bgjd, with ebjd x bgjd you should get close to 50%, so i like the upper part of the article but it starts to lose merit at the end IMO (and i support the argument of it being recessive gene...)
