9-bar x 14-bar

[RogueDiscus]

I've got a snakeskin pair I've been raising fry from. I get the expected mix of 9-bar turqs and 14 bar snakeskins. Wondering, is the 9-bar turq dominant? Do turqs and snakes follow the basic Punnett square genetics? I'm wondering about the outcome of F1 pairings, maybe turq and snake mixes.

[CliffsDiscus]

I've got a snakeskin pair I've been raising fry from. I get the expected mix of 9-bar turqs and 14 bar snakeskins. Wondering, is the 9-bar turq dominant? Do turqs and snakes follow the basic Punnett square genetics? I'm wondering about the outcome of F1 pairings, maybe turq and snake mixes.

Yes, the 9 bars are dominate, originally the snakeskins (14bars) came from the red turkis.
If you pair up the 14 bar with another 14 bar snake
your still going to produce 8 and 9 bar turkis.

[RogueDiscus]

Well, that's what's confusing. If turq is dominant, then the snakes would have to be homo zygotes. So snake x snake would have no turq. Turq x turq could have some snakes (25%). But maybe it doesn't work that way.

[brewmaster15]

There has to be more to snakeskins genetics than dominant and recessive like we normally think of it. The reason I say this is because if you cross a 14 bar snakeskin to a wild green discus you will get about 1/2 14 bars snakeskins in your f1 offspring. I've done this cross multiple times now. If 14 bar snakes were recessive to 9 bar you would see zero Snakes F1 ...but all would be heterous zygous for snakeskins. Thats not what we see though even when you cross a domestic non-snake to a 14 bar snakeskin you get about half 14 bar snakeskins...

Pair 2 14 bar snakes and as cliff said you get some that are not 14 bars.

I think theres multiple genes involved in some way..alls I know is they are definetly not following your typical genetics for a trait.

[alron2]

This hurts my head reading this, reminds me how I felt in engineering school 50 years ago. I think I will find some discus pictures to look at.
Ron

[nc0gnet0]

14 bar is dominate. SS's are almost always heterozygous, with a good chance that homozygous is fatal. That's why you always get a 50/50 split when crossing a SS to a 9 bar.

[brewmaster15]

14 bar is dominate. SS's are almost always heterozygous, with a good chance that homozygous is fatal. That's why you always get a 50/50 split when crossing a SS to a 9 bar.

Rick and I just discussed this by phone for a bit..a long Bit.

I hate to re-hash it but I will per Ricks Suggestion.

I do not believe that Snakeskin 14 bar and 9 Bar (aka wild type) patterns are the same gene, in simple mendel genetics. That genetics is based on one trait, one gene.

1 )First off, if 14 Snakeskin were dominate over 9 bar you would see 14 bar as the dominate trait we see in Discus. It is not. It also is rare as heck in wild populations.

2) the 14 bar form is not one trait change..its many. You get smaller scales, tighter patterns, 14 bars vs 9 to name the major ones.

3) If 14 bar snakes were dominant.. How is I can breed a 9 bar snake skin x wild discus and get 14 bar offspring as well as 9 bar offspring? I have done this..

4) If I take a 14 bar snake and cross it to a 9 bar wild... I get about 1/2 14 bar snakes. If Snakeskin were homomzygous dominant.. my f1's would all be Snakeskin 14 bar SS (14 bar Snake) x ss ( normal wild type) yield all Ss fish. These would be fish that looked like Snakes. If the Snakeskin 14 bar gene were double recessive, my cross would all look wild yet carry the Snakeskin gene.


Where is the problem then? The problem is we can't tell by looking at a fish what its carrying as a recessive gene... just it dominant traits. Based on this the prevailing theory is as follows.

The common theory on 14 Snakeskins is that they are actually heterozygous for 14 bar.. Meaning they carry a dominant trait for 14 bar and a recessive trait foir normal 9 bar (wild type) . This is why when you cross a 14 Bar with a 14 Bar fish you get a mix of Snakes and 9 bar wild types. That Simple mendelian genetics also means you should get offspring that are Homozygous for 14 Bars...(25 % offspring) . and if you were to breed those each other you would according to Mendelian genetics have batches of offspring where all the fry were 14 bar Snakeskin. Unfortunately , this has not been documented.It doesn't seem to ever happen. The only way this might be explained in Simple Mendelian genetics is if the homozygous 14 bar Snakeskin Trait were conveniently a lethal combination. This is an effect that happens in some genetics...but it hasn't been proved here...its been assumed because its what makes the simple Mendelian genetics fit with snakeskins so thats what commonly believed to be the case. K.I.S.S. (keep it simple stupid) at its best!

In my crosses of wilds to domestics I am seeing results that indicate other genes are involved. It really does not make sense to me that a trait that is statistically minor in a population (heterozygous 14 bar ) would actually be dominant to the most wide spread form of the trait (9 bar wild type) .. It stands to reason that we would see more wild snakeskins if this were true in wild populations and that we see more domestics that are 14 snakeskins. I honestly don't know of any traits in the wild that would be dominant yet have not established themselves in a population as such, maybe some one does know of example . Alternatively, The Snakeskins I have crossed can't have been Homozygous Dominant for the 14 bar trait or I would seen all Snakeskins in my first batch of fry (f1) or I would have seen none in my offspring if the Snakeskin was homozygous recessive for the 14 bar trait..

So either all Snakeskin 14 bars are Heterozygous fish for the trait, and double doses of Dominant are lethal (unproven) or theres multiple genes involved and "Snakeskin" is not a trait that neatly fits into Simple Mendelian genetics.

One easy way to answer this question is for someone to grow out their F1 one 9 bars in their Domestic Cross of two 14 bar snakeskins and breed two 9 bars to each other.. These f2 batch fry should have zero snakeskins if the theory that 14 bar Snakes are all Heteozygous, lethal double dose, and dominant for Snakeskin is accurate.


I don't think we have enough info yet to say.. but I really don't like to assume that all living 14 bar Snakeskins are Heterozygous for the trait and that Homozygous 14 bar snakeskin is lethal combo and why we don't see whole batches of Snakeskins...yes it all fits nicely once you get past the fact that it doesn't sound probable given all the other points I have raised. I also don't like assuming that multiple genes are involved, but when I look at this , thats what I see as most probable.. As a scientist, assumptions make me cringe, but sometimes thats all we have to work with ..pick which poison sits best with you for the time being and keep digging.

Understandably I am in the minority on this one

al

[nc0gnet0]

Rick and I just discussed this by phone for a bit..a long Bit.

I hate to re-hash it but I will per Ricks Suggestion.

54564180.jpg

Sorry, i was having a Skip moment

[RogueDiscus]

Thanks Al for taking the time to write that all out, and to you and Rick for your discussion. I remember reading about the lethality issue, but my gut feeling was that it was more complicated. I hope others enjoy the info too. I still need to send you some good picks of the bar-less fry I mentioned I've gotten from the pair. Very interesting.

[nc0gnet0]

I do not believe that Snakeskin 14 bar and 9 Bar (aka wild type) patterns are the same gene, in simple mendel genetics. That genetics is based on one trait, one gene.

Quite possibly poly genetic. But, I believe sometimes poly genetic traits can "behave" in a single gene manor. the reason for this is during recombination, sometimes multiple genes are linked. (pardon my laymans terms here).

1 )First off, if 14 Snakeskin were dominate over 9 bar you would see 14 bar as the dominate trait we see in Discus. It is not. It also is rare as heck in wild populations.

I will admit, all of my observations have been on a domestic discus level. I have not done any wild 9 bar to domestic 14 bar cross's. I do know that when working with domestics, the model I speak of works fairly consistently.

2) the 14 bar form is not one trait change..its many. You get smaller scales, tighter patterns, 14 bars vs 9 to name the major ones.

This is an interesting point, but when I answered I was addressing the issue of the bars themselves, and not the other traits you mention. I think we have to "Define" first of all, exactly what a SS is. I was merely defining SS as a discus fish with 14 bars vs 9. Your applying a much more broad definition of the term to encompass number of scales, tightness of pattern, etc. Now, I am not saying this definition is wrong, just pointing out we are applying the term a bit differently. For instance, I have on occasion seen discus from a cross of 9 bar to 14 bar, or even 14 bar to 14 bar, have a percentage of fish with niether 14 or 9 bars, but rather 3,5 or 7 bars. many times these fish have increased scale density. To clarify, would you call these fish ss?

3) If 14 bar snakes were dominant.. How is I can breed a 9 bar snake skin x wild discus and get 14 bar offspring as well as 9 bar offspring? I have done this..

In my example, the 14 bar gene(s) is dominant and being carried heterogeneously by the SS parent. This explains why you get roughly 50% SS offspring. Furthermore, in the model I propose, a homogeneous SS is a combination that is almost always fatal (embryo dies in-vitro), so you never see any homogeneous SS's.

*edit I misread this post. 9 bar SS. I have never worked with one, nor was I referring to anything with 9 bars as being a SS. Could this be unique to either the 9 bar or 14 bar fish?

[nc0gnet0]

4) If I take a 14 bar snake and cross it to a 9 bar wild... I get about 1/2 14 bar snakes. If Snakeskin were homomzygous dominant.. my f1's would all be Snakeskin 14 bar SS (14 bar Snake) x ss ( normal wild type) yield all Ss fish. These would be fish that looked like Snakes. If the Snakeskin 14 bar gene were double recessive, my cross would all look wild yet carry the Snakeskin gene.

I am saying neither is the case, as all SS's are heterozygous, because, in my explanation a homozygous SS dies in-vitro

Where is the problem then? The problem is we can't tell by looking at a fish what its carrying as a recessive gene... just it dominant traits. Based on this the prevailing theory is as follows.

no arguments there, and everything I am saying is based on my observation, and I am not presenting them as fact. I am the first to acknowledge that many of the mutations we often try to explain using simple one gene mutation examples are in fact a little more complicated than that.

The common theory on 14 Snakeskins is that they are actually heterozygous for 14 bar.. Meaning they carry a dominant trait for 14 bar and a recessive trait foir normal 9 bar (wild type) . This is why when you cross a 14 Bar with a 14 Bar fish you get a mix of Snakes and 9 bar wild types. That Simple mendelian genetics also means you should get offspring that are Homozygous for 14 Bars...(25 % offspring)

Not if that combination is fatal

and if you were to breed those each other you would according to Mendelian genetics have batches of offspring where all the fry were 14 bar Snakeskin.

Again, not if the homogeneous iteration of the mutated gene was a fatal combination.

Unfortunately , this has not been documented.It doesn't seem to ever happen. The only way this might be explained in Simple Mendelian genetics is if the homozygous 14 bar Snakeskin Trait were conveniently a lethal combination. This is an effect that happens in some genetics...but it hasn't been proved here...its been assumed because its what makes the simple Mendelian genetics fit with snakeskins so thats what commonly believed to be the case. K.I.S.S. (keep it simple stupid) at its best!

It does seem to fit, and too date is the best explanation I can think of. Doesn't make it true, I will admit.

In my crosses of wilds to domestics I am seeing results that indicate other genes are involved. It really does not make sense to me that a trait that is statistically minor in a population (heterozygous 14 bar ) would actually be dominant to the most wide spread form of the trait (9 bar wild type) .. It stands to reason that we would see more wild snakeskins if this were true in wild populations and that we see more domestics that are 14 snakeskins.

This is a very good point. I don't have a definitive rebuttal, only some possibilities as to why this is the case:
1) the mutation does not happen in the wild often enough for the mutation to get a foothold and spread.
2) natural selection has the mutated discus less preferable as breeding partners
3) The SS mutations are inherently weaker than there 9 bars siblings

I honestly don't know of any traits in the wild that would be dominant yet have not established themselves in a population as such, maybe some one does know of example . Alternatively, The Snakeskins I have crossed can't have been Homozygous Dominant for the 14 bar trait or I would seen all Snakeskins in my first batch of fry (f1) or I would have seen none in my offspring if the Snakeskin was homozygous recessive for the 14 bar trait..

covered

So either all Snakeskin 14 bars are Heterozygous fish for the trait, and double doses of Dominant are lethal (unproven) or theres multiple genes involved and "Snakeskin" is not a trait that neatly fits into Simple Mendelian genetics.

ok

One easy way to answer this question is for someone to grow out their F1 one 9 bars in their Domestic Cross of two 14 bar snakeskins and breed two 9 bars to each other.. These f2 batch fry should have zero snakeskins if the theory that 14 bar Snakes are all Heteozygous, lethal double dose, and dominant for Snakeskin is accurate.

I have done that, and all fish were 9 bar fish. But, my sample size is too small to say that a 14 bar fish couldn't happen. but, too date, I have never gotten a 14 bar fish from two 9 bar fish.


I don't think we have enough info yet to say.. but I really don't like to assume that all living 14 bar Snakeskins are Heterozygous for the trait and that Homozygous 14 bar snakeskin is lethal combo and why we don't see whole batches of Snakeskins...yes it all fits nicely once you get past the fact that it doesn't sound probable give all the other points I have raised. I also don't like assuming that multiple genes are involved, but when I look at this , thats what I see as most probable.. As a scientist, assumptions make me cringe, but I sometimes thats all we have to work with ..pick which poison sits best with you for the time being and keep digging.

Understandably I am in the minority on this one

[brewmaster15]

Rick,

Furthermore, in the model I propose, a homogeneous SS is a combination that is almost always fatal (embryo dies in-vitro), so you never see any homogeneous SS's.

almost doesn't cut in a lethal mutation. Thats why is called lethal if the theory is thats this is case, then it really should be all or nothing... can't put your toes in, take the plunge

al

[nc0gnet0]

Now, let me bounce something else off you, and I am just thinking out loud here. What if the 9 bar vs 14 bar is a one gene trait, and the pattern and scale density are controlled by different genes that are close in proximity to the 9 bar gene, and most often, yet not always linked during recombination. This would mean that a 14 bar/higher scale density/tighter patterned fish occurs because a chain of genes are being transfered together, but once in a while this chain is broken (maybe because of the inclusion of another mutation, like the BD gene).

I am sure my wording could be better, hope you understand what I am trying to convey.

[nc0gnet0]

Rick,
almost doesn't cut in a lethal mutation. Thats why is called lethal if the theory is thats this is case, then it really should be all or nothing... can't put your toes in, take the plunge

al

Ahh, but there are conditional lethal alleles, but your right. I only said almost always as I was trying to allow for the exception to the rule. I was guessing that a homogeneous SS might be so weak that it almost never survives, but survival was possible, although extremely remote. I am not saying that was the case, but allowing for it. I have never seen one.

[brewmaster15]

Now, let me bounce something else off you, and I am just thinking out loud here. What if the 9 bar vs 14 bar is a one gene trait, and the pattern and scale density are controlled by different genes that are close in proximity to the 9 bar gene, and most often, yet not always linked during recombination. This would mean that a 14 bar/higher scale density/tighter patterned fish occurs because a chain of genes are being transfered together, but once in a while this chain is broken (maybe because of the inclusion of another mutation, like the BD gene).

I am sure my wording could be better, hope you understand what I am trying to convey.

I suppose its possible Rick, but its pretty consistent if this happens.It would also basically lend credence to my idea that more than one gene is involved in what we term "Snakeskins".



Heres one for you. If your assumption /theory of lethal homozygous 14 bar were a bust, how else would you explain what we see in Snakeskin Genetics?

al