Lizzy schreef:Na mij reageerde er iemand die Westie's heeft en een stamboomdatabase waar meer dan 400.000 honden in staan. Zij schreef dat ze gelooft dat de data incorrect is. Dit is de reactie van Carol:Dus ze heeft nog niet gereageerd op de lage coi van de Sloughi? Want dit antwoord gaat over een omgekeerde vraag, dat de coi van de westie in het echt lager zou zijn? 10 honden vind ik sowieso best weinig ...
Carol Beuchat : There is no reason to question the data. These are actual measurements of homozygosity made on the DNA. You can actually look at the data and SEE the SNPs that are homozygous (I posted some examples in this group on 25 November if you scroll down).
Pedigree analysis produces an estimate of COI that is a probability based on the pedigrees. Pedigree estimates are often lower than DNA measurements because any mistakes in the database or missing information will result in an underestimation of the COI. The pedigree-based prediction also assumes that all of the animals in the very first generation of the database are unrelated and not inbred, so that the COI value is what is expected to accumulate SINCE that first generation (which is also why only using 5 or 10 generations of data is so unreliable).
I have written several blog posts about the bad situation terriers are in (check the blogs on the ICB website or search for terrier), and I also have a completely independent set of data drawn from MyDogDNA which also indicates that inbreeding in Westies is extremely high.
(http://www.instituteofcaninebiology.org ... reeds.html - scroll down)
To convince you, have a look at the "runs of homozygosity" - blocks of homozygous markers from the same data as the original post. There is a tutorial (part 1 and part 2) here that you should look at first (but it's not as complicated as it looks) -
http://www.instituteofcaninebiology.org ... l-pt1.html
Then look at the picture, which shows the data for Chinook, Berners, Westies, and Scotties. (red is heterozygous, blue is homozygous).
I don't doubt for an instant that these data are not representative of Westies. Of course, the clever thing to do would be run the DNA on some dogs that you have good pedigreed info on and we can actually compare.
Carol Beuchat Have a look at the data for Westies from MyDogDNA. You can see that even though the inbreeding is very high, the populations in different countries are a bit different, and also that the clusters are tightest for the US and UK dogs (i.e., there is less genetic variation). This indicates that there is some genetic diversity in the breed, but there is no way to tell from their scatter plot how much. The ICB Breeder Tool will compute the actual "genetic distance" between any two dogs - the fraction of their genomes that are the same. That information for Westies would allow breeders to reduce inbreeding by making some strategic breeding choices. But you can see by the ROH data, trying to "improve" the breed when everybody is homozygous for the same genes is going to be next to impossible.
https://www.mydogdna.com/crm/index.html ... ationships
Dan schrijft iemand: I still would like the total sample size for Westies. A sample of greater than 100 dogs is still extremely small, given the large number of westies found around the world.
Carol Beuchat : I think they used 10 dogs per breed for all but one or two (for which there were 9), but the link to download the paper is below and you can check. These dogs were AKC registered (so US breeding for the most part). As you saw with the MDD data, dogs in different countries have genetic differences, but if you look at the inbreeding (on the other tab of westie data), they are ALL significantly inbred.
As I said, from all the data I've seen, I don't have any reason to suspect that there are large populations of Westies someplace with inbreeding levels of 10% except perhaps from puppy mills, which are less likely to be producing highly inbred dogs because inbreeding depression would reduce their profit.
I could certainly have a look at your pedigree database. I would be very interested to see if there are populations that are less inbred, because they would provide opportunities for improving genetic diversity.
En dan verwijst ze naar het onderzoek: http://dmm.biologists.org/content/9/12/1445
. Ik weet natuurlijk niet hoe random die 10 genomen zijn....
