Lusia at Lassie Gets Help puts forth Dewi Tweed, the 2010 International Supreme Champion sheep dog as proof that the “genetic bottleneck” in Border Collies is benign or perhaps a myth.
Richard Millichap’s most awesome Dewi Tweed gathers sheep in the Welsh mountains. Enjoy! [For those interested in the border collie’s “genetic bottleneck,” Kinloch has a link to Tweed’s pedigree, with the inbreeding coefficient numbers listed for his ISDS parents and grandparents.]
Sadly, COIs for one dog’s parents and grandparents don’t really tell the story of what’s happening with the breed. Especially when you’re only looking at 6 generations. But let’s look at Dewi Tweed anyway.
Here’s the published pedigree:
And here’s a Legend to explain what the notation means:
The first thing you’ll notice is all the green. Every green dog on the pedigree has major trial results. I count 18 of the 62 dogs on the pedigree with major trial results. You’ll notice that the top of the pedigree is dominated by Bwlch Taff, a major sire with 715 registered puppies to his credit, and whose genes alone comprise over 3% influence on recent dogs. For reference, Wiston Cap has a current breed influence of over 14%, making him literally the great-grandfather of the breed.
In a normal pedigree with no inbreeding, parents each have a 50% influence, grandparents a 25% influence, and great grandparents 12.5% influence.
In the case of Dewi Tweed, popular sire Wiston Cap has a blood influence of 18.4% even though you have to go back at least 6 generations before you find him on the pedigree. So even though he’s been gone for more than 30 years, he still holds more realestate in Dewi Tweed’s pedigree than a great grandfather. But that measure alone doesn’t account for Wiston Cap’s impact on Dewi Tweed. The COR is what’s called the Relationship Coefficient, and it estimates the percent of genes passed down from any specific ancestor to the target dog. Wiston Cap’s COR on Dewi Tweed is 26.7%. So although he only takes up the equivalent space of a great grandfather, Wiston Cap is like a grandfather to Dewi.
This isn’t too surprising given that Wiston Cap appears 156 times on a full pedigree of Dewi Tweed between the 6th and 16th generations, with the 1st generation being the parent dogs, not the target dog.
In fact, Dewi Tweed has blood from 9 of the top 10 most popular Border Collies.
What is clear from the chart is that Dewi Tweed is the product of a concerted effort to breed to a very select few popular dogs. It’s also clear that those few poplar dogs are also highly related.
This is the popular sire effect. Just look at how some of them like Ben represent a very small theoretical percent of blood but a commanding influence on the genetics. The concentration of genes in the gene pool through inbreeding and line-breeding have allowed Ben to pass down his genes over 17 times more than would be expected from his 15 appearances on the pedigree. You can’t magnify genes within a gene pool without marginalizing other genes.
It’s not surprising that the youngest popular sire Wisp (who has still managed to romance his way into the top 4 studs of all time) doesn’t have influence on Dewi Tweed; as of the year 2000, roughly 80% of the puppies born did not have any influence from Wisp yet. There simply hasn’t been enough time for him to work his way into more lines, but we’ve already experienced his exponential rise to fame and his influence is leveling out at 4%.
Although Donald McCaig recently said:
I’ve heard the complaint that Border Collies aren’t any healthier than other purebred dogs, that pedigrees w/o Wiston Cap (d 1979) are rare. True about Cap. And intensive breeding to a single sire was, genetically, a risky idea. As it happens, the community dodged the bullet: Wiston Cap didn’t have anything wrong with him. And there hasn’t been another Wiston Cap – the community is “flavor of the month” and what I want in a dog aren’t necessarily the same combination of virtues and vices another equally qualified handler might want.
The truth is that there HAVE been many other popular sires who have cemented their place in the breed forever and consequently narrowed the gene pool. Here is a chart of all of them, Wiston Cap is #31154. He isn’t even the most popular sire. That honor belongs to Cap 3036 who would have still surpassed Wiston Cap even if Wiston Cap wasn’t so highly inbred on Cap 3036 in the first place [~24.5% of Cap’s genes are found in Wiston Cap]. You can see Cap’s rise to dominance happened even before Wiston Cap was born.
Luisa noted that Dewi’s parents aren’t very inbred when when we look at only very recent generations, 6 generations in the case of the supplied chart. Well, a COI6=4.4% for the sire Lad isn’t a very impressive number. That level still indicates active line-breeding, as we can see, the same sire Bwlch Taff appears twice in the third generation. The dam’s COI6 is much better at 1%, but we can still see inbreeding on common ancestors like A. Owen’s Ben.
I entered 3149 ancestors of Dewi Tweed into my pedigree program and ran Dewi Tweed’s COI6 and got 2.27% More interestingly, I ran Dewi Tweed’s FULL COI calculation where you take his entire known pedigree into account. This is a superior calculation and represents the true degree of theoretical allele concentration due to inbreeding and line-breeding. Before access to genetic programs such calculations were impractical, thus the popularity of more crude measures like a COI6. Dewi Tweed’s full COI is 9.3%
Again, while the recent breeding on Dewi Tweed’s pedigree doesn’t top the charts in gross inbreeding it does not offer us any consolation that a genetic bottleneck does not exist in the Border Collie breed. In fact, his pedigree proves that such a bottleneck does exist.
Dewi Tweed is a typical example of what’s happening breed-wide: a declining interest in breeders using excessive levels of inbreeding (like father-daughter, litter mates, etc) but the overall COI of the breed still rising at an alarming rate. COI6 numbers are falling, but full COI numbers are rising. That fact tells us that we’re past the turning point. There’s no way to out-cross our way out of increasing COIs using only registered dogs or following the same breeding trends we have been, specifically over-breeding the “flavor of the month” trial sire far and wide.
I applaud Luisa for recognizing an amazing dog that was bred and handled by an exceptional handler, but she goes too far to suggest that his pedigree assuages what should be a serious concern over the future genetic health of the Border Collie breed.
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Maybe the reason Border Collies are relatively healthy is because they’ve been linebred closely on healthy dogs, so proven by close line/inbreeding — rather than bringing in unknown genes from outcrosses. Remember, sooner or later those outcrosses become linebred to themselves, the first time anyone breeds two descendants of said outcross. And then, perhaps too late to go back and undo its influence, you find out what negative genes came in from that outcross.
This is why COI is not really meaningful. A genetically-healthy dog in the pedigree 100 times does far less ‘damage’ than a lethal-carrier in the same pedigree only TWICE.
The real trouble today is that the term “genetic diversity” is being misused to mean “every dog carries lots of different genes, has a low COI, and is as outcrossed as possible”. In fact it means no such thing. Correctly used, it means there are lots of UNRELATED gene pools (which by definition will be linebred within each separate gene pool) — so if Line A goes pear-shaped, Line B is not affected and the breed continues. However, if you outcross Line A to Line B and v.v., now they both carry all the same defects, and if some defect proves fatal, BOTH lines are lost.
But the real trick is letting natural selection do its job. Don’t save or breed from weak puppies. This is why wild animals, which when actually DNA-tested were found to have an average COI around .25, are relatively free of lethal defects despite being heavily inbred. (You don’t think that herd buck examines pedigrees before he screws his daughters from last year’s crop, do you??) It’s also why they are so nearly phenotypically identical.
In my own kennel, I have not done an outside breeding since 1994 (and I regret most of those I did before that). Now at 13 generations, my dogs never see the vet, and my longevity is going UP (now averaging about 14 years in good health). I don’t outcross, and I let natural selection do its job.
Border Collies are relatively average despite having a very un-average breeding metric in sheep trials.
While they don’t suffer from conformation bred diseases like too-small skulls [CKC Spaniels] or crippled rear ends [German Shepherds] or white linked deafness [Dalmations] or spinal issues [Rhodesian Ridgebacks], their incidence of hip dysplasia and joint disease is middle of the pack. And the pack isn’t in a good place.
Their incidence of cancer, allergies, skin/coat issues, eye issues, etc. are, again, average. The trial culture thinks they are doing better because their activity is better, but their breeding practices are not. So while they avoid the obvious defects like snubby noses or excess skin or roached backs or aggressive selection for a single coat color or other physical trait, they are still paring the gene pool down, smaller and smaller.
> relatively healthy is because they’ve been linebred closely on healthy dogs, so proven by close line/inbreeding
Healthy [so-so] not BECAUSE of, but in-spite of inbreeding. Border Collies are lucky to not be like some breeds where there were literally a mere handful of founders.
> unknown genes from outcrosses …outcrosses become linebred to themselves …too late to go back and undo its influence… negative genes came in from that outcross.
Unknown is really a meaningless term here. Smart outcrossing isn’t about pulling a random dog from a black bag. The truth is, so much more is unknown than is known. The idea that you must breed to the known is silly, if that’s the case we should always breed mother to son and father to daughter, litter mates to litter mates.
The spectre of “unknown bad genes” is unsubstantiated and a figment of the “purity” element of elitism and eugenics.
> COI is not meaningful
The purpose of outcrossing is to increase heterzygosity and decrease homozygosity. The purpose of inbreeding is to increase homozygosity. COI is a measure of how much you have increased homozygosity as a function of your breeding patterns. It is highly meaningful. It is also important.
> Line A, Line B, etc
I like your circumspection about what it can mean to have diversity within a gene pool, but it’s not good to just divide up lines and continue to whittle them down and inbreed them. If we kept following the model you suggest, throwing out lines when they go pear shaped, then we only decrease diversity in the long run.
It’s also healthy for the gene pool to mix lines and develop new ones, each little pool serving as a source to outcross to.
It’s also healthy to bring in new blood from other breeds. Sure, a BC might not need anything from a show Chihuahua, but we could gain from bringing in other herding blood, without having to give up much at all. Certainly not losing things that could be brought back in.
For instance, it wouldn’t ruin the breed to bring in some McNab blood, some Aussie blood, some English Shepherd blood. We could then focus on maintaining the must have elements of the breed (i.e. getting back to homozygous traits for “eye” etc.) while not weeding out the new diversity we brought in for all the other genes (like immune system, liver function, bone strength, heart health, etc.).
See, when we inbreed for a few specific traits we are also inbreeding on traits that we have no interest in making homozygous. Since there are a lot more genes that control things we’d rather have diversity in, we have the potential to do a lot of harm while we “breed true” on a few select genes.
> Line A pear-shaped, Line B not, outcross, both are lost
This is really silly. Genes are not communicable viruses, they are not Ebola. And no disease becomes more potent when it is crossed.
Nor can you preserve what B is by inbreeding on B. You will end up with half-B. The only way to preserve what B is, is to clone B. If B has any heterozygosity, it will be lost with continued inbreeding. So no, you can’t maintain health by just inbreeding. Every single disease that you are avoiding by having one good copy of a gene, you will risk expressing.
Your dog might have one good copy of the stomach juice gene, one faulty copy. One good copy is enough to produce the right chemicals in the stomach. Inbreed your lines down and then you’re stuck with two copies of the bad gene and suddenly you have a picky eater in one dog, a crappy coat in another because of vitamin deficiency, another eats poop, and one gets esophageal cancer. You might never get an actual disease name, or a diagnosis, or even a consistent series of symptoms, but you’ve gotten less healthy animals.
> wild animals, DNA-tested, COI .25
COI is a theoretical number, not empirical. So I don’t know how DNA testing would tell you the COI. BOTH are trying to tell you something about the homozygousity. The COI is an estimate of how much heterozygosity you have created by inbreeding. It ASSUMES that all the ancestor dogs are homozygous and unrelated. This is not a valid assumption in the real world. SO, COI is a VERY CONSERVATIVE estimate.
DNA would tell you the actual level of homozygosity. So please link the study you refer to so I can read what they were actually measuring!
From what I know of wild animals, yes, they do inbreed, but not over hundreds of generations. New blood comes in all the time. A new sire moves into town from a different gene pool, a different alpha couple takes over. There is plenty of mixing it up.
In very unique places, like isolated habitats with few animals, we do have extreme inbreeding. This is generally not a good thing and these populations are often very fragile.
And about that buck examining pedigrees? Well, there are recent studies that show that wild animals do select against inbreeding!
http://www.livescience.com/animals/080417-inbred-smell.html
The main argument they have is the cheetah.
What Reziac is saying is that his dogs are like cheetahs.
Cheetahs are heavily inbred but are relatively healthy because they experience natural selection.
However, cheetahs have lots of reproductive problems.
They are not immune to the problems of being inbred.
Which reminds me:
There is a population of cheetahs in Iran that occasionally ranges into Afghanistan and Pakistan.
These are the only remaining Asiatic cheetahs. Cheetahs used be found through the Middle East, up towards the Caspian, and down into the Indian subcontinent.
I bet the COI’s on those animals, if they could ever be calculated, are going to be terrible.
Balkanized gene pools are likely to kill off the African lion, even though it is quite numerous. There is little to no gene flow between lion populations, and those in the Ngoro-Ngoro crater are very heavily inbred. Reproductive problems already exist, and this looks like it will be the future of lions unless something is done.
In dogs, we have every opportunity available to prevent a cheetah or African lion situation, but because dogs are a cultural construct, they are at the mercy of the cultural norms of the humans who breed them. Our culture, our ideas, and mores will harm the dog as much as the extreme natural genetic bottleneck in the cheetah and the habitat fragmentation bottleneck in the African lion.
This is one of the greatest tragedies in the history of life on this planet.
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Hey Christopher, can you help me on something?
I have learned more about border collie genetics here than with any breeder I know. I sometimes think some breeders avoid your website, as they are afraid of the truths you show here.
Can you tell me what pedigree program you use?
Thank you!
Anna
Oh, they do avoid my website Anna, I didn’t make many friends when I started to question the breeding assumptions and practices with a rational mind. The breed has been through the work-show civil war and most people have already had their fill of arguments and questions. They’ve chosen their sides, built their walls, and are content to rot behind them. Criticism of the show world automatically makes you a working elitist and criticism of the trials automatically makes you a fancy sympathizer.
I’ve never minded going my own way and forging my own path versus kissing up to the power brokers and “paying dues.” Border Collies are no different. I’ve had them since years before the split and I’ll have them until I die, I know what I like and I’m always open to learning more. I just won’t sign my name on any contract that says there is one true path and you must worship the priesthood instead of dogs.
The pedigree program is called PedX by Breedmate. http://www.breedmate.com/
If you’re looking for help with Border Collie pedigrees, I suggest the yahoo group: http://groups.yahoo.com/group/BorderColliePedigrees/
There is also a must-read site that covers many aspects of Border Collie population structure here: http://www.bcdb.info/index.htm
Cheers.
Thank you very much Chris!
That is precisely what I see happening. And what happened to me, actually. I was part of this show/trial war for too long, fighting for all sides really!
When I first found your website, I believed in what show breeders said about health checks and sound structure and just assumed you were one of those who admired working but unhealthy dogs (funny how the marketing gets us, huh?).
Then I started training agility and all the marketing they did fell apart! I fought for the working cause for long after that, but I’m getting smarter and smarter (thank god!) and less inclined to pick sides.
Then a few months ago I ended up here again! And I just couldn’t believe how much I agree with you now. Guess it was a good road and I’m glad I’m not looking for a finish line anymore!
Thanks for all the tips! I have lots of full COIs to calculate now (I’m seriously afraid of what I might find…).
Keep the good articles coming!
Anna
Hey Chris,
I’ve purchased PedX, thanks for the tip! Can you swap data with me? 🙂