Panda Shepherd - Page 5

[siiighhh!]

Katjo, I strongly suggest you review how basic genetics works.

In order for the border collie type markings to have remained hidden in the gene pool this long, it would have to have been a RECESSIVE characteristic.

A recessive gene cannot suddenly become dominant, as was the case with Frankie, therefore Frankie's colour must have been a spontaneous mutation. Some have brought up the point that Frankie's ancestors were not DNA'd to prove pure GSD ancestry;  however, if they had carried this gene, it would have been expressed (shown up as the BC type markings.)

There is, of course, the possibility that one of Frankie's parents/ancestors was not the one in the pedigree, but a sneaky neighbour's collie than got through the fence. However, DNA tests are now sophisticated enough to show that a dog is of mixed parentage, and I assume this would have been discovered when Frankie was DNA'd.

So, there are only 2 possibilties:

1) The gene was recessive (disproved because Frankie produced mostly pups like herself, showing it was a dominant gene.)  A recessive gene would have produced affected pups ONLY if Frankie was mated to a male that was a carrier for the panda colouration.

2) The gene was a spontaneous mutation for the panda type pattern.

Hm.

A black  GSD (homozygous recessive) can be bred with a  black "carrier" dog of another color(heterozygous) and throw as high as 100% their  recessive color in a litter, even tho genetic prediction only gives it a 1 out of 4, or 25% chance of that recessive color being produced.  It's just up to what happens.

If I breed my black stud male to a lady in Cleveland's blk/red WGR show line female 4 hrs away and she has 4 out of 6 BLACK pups (it happened-October 2008), does that mean my male's black is proven dominant because his color was produced more in the litter? NO, Sunsilver, it doesn't(its already an established fact that black is recessive), but that's what you state in your first possibility. It means nothing more than that dog with the homozygous recessive color happened to throw  their color strong in that particular breeding. Frankie could still be recessive in color, but since she IS the color, she's got the potential to produce none, or ALL like herself, or anything in between. It does not establish dominance or recessiveness in her color at all.

"Apparently, DNA tests on Frankie, the much-publicized Panda sheperd showed a definite gene mutation, which was DOMINANT, not recessive, meaning approximately 50% of the pups he produced would have the Panda colour pattern,..."  -quoted from Sunsilver's earlier posting

I was merely mentioning what I did because you stated the DNA testing said Frankie's color was dominant. I didn't say it was a dominant color, nor do I exactly agree with that, or what you had stated. I just gave my thoughts IF that was possible.

So, things spontaneously mutate in various litters and produce the exact SAME results/markings multiple times in the same breed ? That's not exactly a mutation, then, is it? If it only happened once, yeah. But multiple times? So I don't agree with your second possibility, EITHER.

Funny, I had written my black comparison notes I just shared here earlier but then deleted them for fear I would confuse people. Sounds like maybe I should've went ahead and added them.

Shall you accompany me back to the books on genetics, Sunsilver? Sounds like you might need a refresher, too.

And if Frankie is recessive in color and has produced herself in pattern, then that means the sires she was bred to (which was a few different ones-I only know/remember one by name, maybe 2) all CARRY that same funky Border Collie coat pattern.

Sobering thought, eh?

So, how did these males carry such a pattern-spontaneous mutation, too? Nope. It's in there from the birth of the breed. Dogs can carry things in their genetics without ANY hint of it. A blk/red GSD can be a black carrier with no physical indicators-just documented proof because black was indeed produced from that dog when bred with a black partner.

But it also explains why we see it elsewhere cropping up (the coat pattern/color being recessive and just buried into the genetics). That seems more likely, JMO.

I've bred 4 West German show line blk/red females with no indicators that they were black gene carriers (over 7+ generations have NO black dogs listed in the pedigree-only blk/red show line dogs we would be familiar with-yes, for those of you wanting to jump at that, I know and understand at SOME point black would have to be there, but you might have to go back 20 generations to find a black dog in those girls-you would think such wouldn't be significant that far back, but obviously it IS), but when bred to black, they ALL actually produced a higher than expected 25% possibility to produce that black.  All bred to my black male, by the way, who is DNA profiled and bred under my overseeing and kept in my home secured while the breeding was taking place. 2 of the girls he was bred to were also DNA profiled.

This border collie marking could work the same way his black does, and isn't hard to comprehend.

I'm sorry, katjo, I don't need to take a genetics refresher. I TAUGHT biology in school, and have credit in several university level courses on the subject!

The ONLY way Frankie could produce her own phenotype if she were pure recessive would be to mate with a CARRIER.

Small p equals panda.

Large P equals normal

If she mates with a carrier Pp, she will produce pups that are all in appearance like the male, because normal colour dominates the panda color. However ALL pups will be carriers.

   PP  crossed with pp can only produce Pp (carrier)
   Pp crossed with pp produces 50% carriers, 50% Panda.

I'd do a Punnett square, but I've tried that before on the database, and it just won't line up properly.

The second argument against it being recessive is how come the gene has never shown up before that we're aware of? (Such pups COULD have been secretly culled, I admit.) Liver, blue, black and white genes are ALL recessive, and although black and while shepherds are more common than livers and blues, the gene still pops up now and then.  There is a remote possibility that the gene is so rare that it just hasn't happened before. However, given the amount of inbreeding in the GSD genome, I would be VERY surprised of that were the case.

 

So, things spontaneously mutate in various litters and produce the exact SAME results/markings multiple times in the same breed ? That's not exactly a mutation, then, is it? If it only happened once, yeah. But multiple times? So I don't agree with your second possibility, EITHER.

The passage I've quoted above doesn't make a lot of sense to me, but it seems to indicate you don't understand how Frankie's mutation would be transmitted if it were a dominant gene. Once the gene mutates, it is there to stay. No additional mutations are required to keep it in the gene pool. The only criteria is for Frankie to be bred and have pups.

Now, as for Panda pups popping up in other, unrelated litters, here is a possible scenario. When chromosomes separate during the formation of the sperm and egg cells, often they swap genetic material. The end of one chromosome would break off, and attach itself to another. Suppose that the gene for panda markings was there all along, but was never allowed expression due to other genes on the chromosome inactivating it. Then, it got switched over to another chromosome, where the gene causing it to be inactive was not present. It would now behave as a normal, autosomal dominant characteristic.

I think this is a far more likely scenario for Panda shepherds to pop up in normal coloured bloodlines than for the gene to be a recessive. And Frankie's progeny have proven that the gene is NOT recessive, as I've explained above!

Let's see if I can get a Punnett square to work. Each dog has 2 copies of the color gene. As I said above, let's assume p is panda, and P is normal.

IF panda is recessive, Frankie must be pp. So, if mated to a normal sire, PP:

                           P         P
p                      Pp        Pp

p                     Pp         Pp


So, all pups are heterozygous for the gene, and will appear normal. No way in hell can Frankie produce a panda pup!

If the sire is heterozygous you get:



                   P            p

p                Pp         pp

p               Pp           pp


As I explained in my post above, you get 50% carrier pups, and 50% affected. Now, the actual number of panda pups in the litter will probably NOT be 50%, that's just the statistical likelihood. Frankie could even produce all panda pups.  And yes, if the panda gene is dominant, you will also get ALL panda pups. (You did state this scenario above, as happened with your black GSD's)

Now, we're assuming only 2 different genes are involved in producing panda or normal pups. This is unrealistic. There are a number of different genes involved in canine colour genetics, and geneticists still don't know everything about how they work.

As for the link you posted, may I refer you to another page on the same site:

http://www.pandashepherds.com/genetic_panda_info


With the help of the founding breeder, Ms. Cindy McCann of Ohio, we have analyzed the DNA of Panda dogs and their non-Panda littermates using modern genetic tools. We have found the following:

· The coat color pattern stems from a spontaneous mutation; it was not introduced from another breed or population.

· The novel mutation occurred in the Sire's germ line, and was then passed down to his daughter, who was the only offspring of that sire to show the distinguishing markings.

· In subsequent generations, the Panda pattern has exhibited an autosomal dominant mode of inheritance, consistent with the action of a single gene acting with full penetrance

What I asked was this: the fact that multiple breedings producing these "panda" marked pups not related to one another are ALL also to be considered spontaneous mutations? You mean to tell me we can have multiple occurrances of the exact SAME "spontaneous" mutation? I don't think so. It would negate "spontaneous". And the pattern cropping up is too obviously predictable-its just like the border collie markings.

I, too, have college credit in college biology, with my scientific paper I wrote in 1993 on the Drosophilia being used to teach future Principles of Biology students how to write a scientific paper on a scientific matter.
Without proper testing, there's no way to figure out what exactly caused this situation.

You would have the SAME potential 50% percentage outcome whether Frankie is dominant, PP, OR if she is recessive, pp, and being bred to carrier males Pp. You can Color code things and at least have people able to follow you with Punnitts, like I've done here in the past explaining black.  But also, Punnit squares only theoretically give prediction guidelines-it doesn't mean its what will in fact happen. Two dogs Pp and Pp could produce a litter of non-effected pups (2 blk/reds who are black gene carriers can have a litter of only blk/red pups, even tho there's a 25% possibility for them to indeed produce a black pup).
 

What exists to rule out the males she was bred to weren't carriers-because they didn't look like it? Most are dead now, so no way to find out genetically.

Take a look at Frankie's father Brain (aka "Amp) -does he look like a panda pappa? Not hardly. http://www.pedigreedatabase.com/gsd/pedigree/279451.html 

I have SEEN panda pups via pictures taken by the breeder about 15 years BEFORE Frankie was ever produced (reputable source)-NO relation to Frankie, similar markings but no blue eyes. So yes, such marked pups HAVE existed prior to Frankie-it just wasn't broadcasted as existing prior to then. It wasn't broadcasted because the breeders were rather shocked and ashamed. And yes, German breeders would cull such.

I gave a link to a hoobly ad up there where someone has produced a litter of pups with such markings currently. The mother has it (she's blk/tan but has white on muzzle, up center of forehead, etc), the father is a normal blk/red. The litter pic looks like a GSD is nursing a litter of BORDER COLLIE pups. No relation to Frankie, either, by the way.

"Now, as for Panda pups popping up in other, unrelated litters, here is a possible scenario. When chromosomes separate during the formation of the sperm and egg cells, often they swap genetic material. The end of one chromosome would break off, and attach itself to another. Suppose that the gene for panda markings was there all along, but was never allowed expression due to other genes on the chromosome inactivating it. Then, it got switched over to another chromosome, where the gene causing it to be inactive was not present. It would now behave as a normal, autosomal dominant characteristic."

That makes some pretty good sense, and