Ancestors of dog breeds, focus on the Weimaraner, comparison to other dog breeds including the Sloughi
Summary by Dr. Dominique de Caprona
© de Caprona 2010

All photographs copyrighted to the photographers. Please do not use text or photos for any purpose without asking.

In the study entitled "On ancestors of dog breeds with focus on Weimaraner hunting dogs", R. Kropatsch and collaborators (see references) analyse the mitochondrial DNA (mtDNA, inherited maternally) and the Y chromosome (inherited paternally) of 27 dog breeds, with a special focus on the Weimaraner hunting dog. This study aims thus at understanding the sex-specific contribution at the time of breed formation, a question which cannot be answered with the use of autosomal microsatellites.The Weimaraner is a German hunting pointer breed whose first standard dates back to 1878.

A total of 111 male dogs, 34 of which were Weimaraners, were studied as well as 4 wolves from Romania for comparison (male dogs inherit both mtDNA and Y chromosome, whereas female dogs inherit only the mtDNA). In all, 1947 base pairs of the mtDNA genome were examined, as well as 9 potentially polymorphic markers of the Y chromosome.

Results
20 Y chromosome and 59 mtDNA haplotypes were identified in the 27 dog breeds and the wolves studied. 16 Y chromosome haplotypes and 55 mtDNA haplotypes were identified in the dog breeds.

The Weimaraner: in 34 male dogs of this breed of both varieties, smooth coated and longhaired, 4 distinct Y chromosome haplotypes and 3 mtDNA haplotypes were found, thus showing that at least 4 different males and 3 different females awee the foundation of the German Weimaraner population. 
Y chromosome: Of the 4 haplotypes (Y1,Y2,Y3,Y4), the haplotypes Y1 and Y3 were found only in the short haired Weimaraner. Haplotype Y4 is shared with the Kuvasz and Giant Schnauzer. The Y2 haplotype was found to be the most frequent in the breed (50% of the dogs) and is shared with 7 other breeds (Kuvasz, Schapendoes, Airedale Terrier, Large Munsterlander, Miniature Poodle, Borzoi and Sloughi).
mtDNA: of the 3 mtDNA haplotypes, 2 are Weimaraner specific (M1 and M2). Haplotype M1 is the most frequent (67.7% of the dogs). Haplotype M2 differs from haplotype M3 in only one position (nucleotide 8479 in the ATP synthase subunit 6 gene). M3 is shared with the Standard Schnauzer in this study. 
This study revealed also some inconsistencies in the Weimaraner Studbook Some of the records cannot be be reconciled with these male and female founders indicating some false parentage at some point in time during the past 130 years of Weimaraner breeding.

The Weimaraner and other pointer/hunting breeds
Comparison of mtD-loop sequences of the Weimaraner and the Large Münsterländer in this study with other breeds of pointer/hunting type dogs (German Short-Haired Pointer, English Setter, Deutsch Drahthaar, Epagneul Breton, English Pointer, English Setter) in a study by Parra et al (2008) shows diverse haplotypes. Together 25 polymorphic sites were identified, of which 14 variations in mt D-loop sequences were not observed in the pointer breeds of the Parra et al study., and  5 variable positions detected in the pointer breeds of the Parra et al study were not found in the Weimaraner and the Large Münsterländer. The Weimaraner and the Münsterländer therefore do not share signifant amount of maternal lines with these other hunting breeds.

Other breeds in the study:
The other breeds used for comparison were: Australian Cattle dog, Berger des Pyrénées, Kuvasz, Saarlos Wolfhound, Schapendoes, Dobermann, Entlebucher Mountain Dog, Tibetan Mastiff, Shar Pei, German Pinscher, Miniature Schnauzer, Standard Schnauzer, Giant Schnauzer, Airedale Terrier, Dachshund, Chow Chow, Irish Setter, Large Munsterlander, Weimaraner, Cocker Spaniel, Golden Retriever, Labrador Retriever, Miniature Poodle, Tibetan Terrier, Borzoi, Saluki, Sloughi.

Of these breeds three asian breeds, Sharpei, Tibetan Mastiff and Tibetan Terrier and one German breed, the Dobermann, are completely separated from the others in both their mtDNA and their Y chromosome haplotypes. All others are partially segregated with some sharing of haplotypes with other breeds in the study. 
In addition to the breeds above, breeds which share no maternal lines ( mtDNA haplotypes) with others in the study are the Kuvasz, the Saarlos Wolfhound, the Irish Setter, the Cocker Spaniel, the Labrador Retriever and the Sloughi and breeds which share no paternal lines (Y chromosome haplotypes) with others are the Berger des Pyrénées and the Saluki.

The results of this study also show that this sharing of haplotypes is found across FCI groups among very different looking breeds, they are not restricted to within FCI groups, therefore not supporting the classification of these breeds in the FCI groups.

The Sighthounds: Borzoi, Saluki, Sloughi
This study reveals that the three breeds examined are different in their maternal and paternal lines.

The Borzoi has 2 mtDNA haplotypes, M15 being breed specific, M6 being shared with Entlebucher Mountain Dog and Dachshund, and one Y chromosome haplotype Y2
The Saluki has 2 mtDNA haplotypes, haplotype M40 being breed specific, M5 being shared with Golden Retriever and Berger des Pyrénées, and one breed specific Y chromosome haplotype Y7
The Sloughi has 3 mtDNA haplotypes, M48, M49, M50, all breed specific and has one Y chromosome haplotype Y2 shared with other breeds

In this study, there is no overlap in the mtDNA haplotypes of these 3 breeds, and there is no overlap between Sloughi and Saluki in both the maternal (mtDNA) and the paternal (Y chromosome) lineages
The Y chromosome haplotype Y2, shared by Borzoi and Sloughi is the most frequent in this study, found in very different looking breeds, and for this reason is considered to be the most ancient, potentially in existence before breeds of dogs differentiated and evolved to become what they are today.
Although the number of samples is limited, these results add to what is already known about the genetics of these Sighthound breeds.

The wolves:
All the 4 mtDNA haplotypes and the 2 Y chromosome haplotypes were wolf specific, none were shared with the dog breeds in this study. All 4 wolves samples came from a Romanian population, with perhaps little outcrossing to local dogs. The authors suggest their finding is supported by other studies of wolf populations from Eastern Europe which display spatial genetic structure (Pilot et al. 2006) and geographic haplotype specificity in wolves in other areas (Vila et al 1997).

Conclusion
The results of this study show that both mtDNA and Y chromosome haplotypes were shared across breeds, suggesting common ancient ancestry in both maternal and paternal lines. At the same time a large number of these haplotypes were breed specific.
Regarding the paternal lines (Y chromosome), the authors state: "In the case of haplotype Y2 being the most ancient and additionally the most frequent haplotype in several breeds, this finding could be taken as a hint that dogs generally share a common Y chromosome pool as it was identified for mt genome (Pang et al 2009)"
 
Acknowledgments

      I thank J.T. Epplen for fine tuning this text and all the photographers who permitted the use of their photographs.

References

Kropatsch  R., Streitberger K., Schulte-Middelmann T., Dekomien G. and Epplen J.T. (2010): "On ancestors of dog breeds with focus on Weimaraner hunting dogs", Journal of Animal Breeding and Genetics, Blackwell Verlag GmbH, Germany.

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