GENETIC STRUCTURE ANALYSIS OF TATRA SHEPHERD DOG POPULATION IN AREA OF KRAKOW BRANCH OF POLISH KENNEL CLUB
II. CONTRIBUTION OF FOUNDERS AND ANCESTORS

Maciej Gierdziewicz¹, Bożena Kalinowska², Joanna Kania-Gierdziewicz^1
1 Department of Genetics and Animal Breeding, University of Agriculture, Cracow, Poland
² Department of Swine and Small Ruminant Breeding, University of Agriculture, Cracow, Poland

ABSTRACT

The study examines the contribution of founders and ancestors to the active population of Tatra Shepherd dogs whose records are kept in the herdbook of the Krakow Branch of the Polish Kennel Club. Four-generation pedigrees of 34 Tatra Shepherd dogs, 19 males and 15 females, born in 1995–2007, were used as a material for creating pedigrees of 150 individuals of both sexes (66 males, 84 females). The 34 animals forming the active population were treated as a reference population in the founder and ancestor analysis performed to determine the total and effective number of founders and ancestors, and to identify those with the highest gene contribution to the reference population. It was found that the reference population had 54 founders and 30 ancestors in total. The effective numbers of founders and ancestors were 28 and 16, respectively. The group of main founders, i.e. those with highest gene contribution to the active population, was composed of 32 animals (15 dogs and 17 bitches). Five founders (3 males and 2 females) contributed from 4% to over 7% of genes, 13 animals from 2% to 4%, and the others only 1–2%. The group of main ancestor comprised 22 animals (14 males and 8 females). Among those, 5 individuals made the gene contribution from 6% to 15%, and the rest, up to 5.5%. Eight individuals were both main founders and main ancestors.

Key words: effective number of ancestors, effective number of founders, founder contribution, genetic structure, Tatra Shepherd dog.

INTRODUCTION

The Tatra Shepherd dog as a breed (FCI Standard No 252a) has been known since 1967. Originally, it was called "liptok", and the first breed standard was established by Prof. M. Trybulski. The breed belongs to the Canis familiaris inostrancevi group which comprises many pastoral and molossoid breeds. According to the current standard, it is traditionally used as a flock guard dog but can also be a companion dog or a therapy dog. The Tatra Shepherd dog has very strong bones, long white coat and floppy ears, and bears strong similarity to Tibetan Mastiff whom it is probably descended from. The ancestors of the breed were brought to Europe in the 4^th-6^th centuries A.C. by Huns and settled in Hungary. In the 15^th century, the Tatra Shepherd dog was bred by Wallachians settled in the Tatra Mountains. Many dog breeds in Europe, e.g. Slovakian Chuvash or Maremmano-Abruzzese, are closely related to Tatra Shepherds; they look very similar, and also have a white coat [14,17].

The Tatra Shepherd dog is strong and determined, with good working ability. It is also extremely intelligent and alert, which makes it useful as a guard dog. On the other hand, its friendliness towards children and domestic animals makes it an excellent companion [18].

The aim of the study was to determine the genetic contribution of founders and ancestors to the active population of the Tatra Shepherd dogs recorded in the herdbook of the Krakow Branch of the Polish Kennel Club.

MATERIAL AND METHODS

Four-generation pedigrees of 34 Tatra Shepherd dogs (19 males and 15 females; active population i.e. breeding animals), born from 1995 to 2007, were used. For the calculations those pedigrees were edited to obtain 150 one-generation pedigrees. The active population of 34 animals was treated as a reference population in a founder and ancestor analysis. The total and effective numbers of founders and ancestors were estimated, and the founders and ancestors with the highest gene contribution to the reference population were identified.

The effective number of founders (f_e) and the effective number of ancestors (f_a) were calculated according to the method proposed by Lacy [11,12] and modified by Boichard et al. [1,2,3]. According to Lacy [11,12], a founder is an animal without known ancestors or without pedigree information. Founders are mostly animals from the oldest generation. Following the definition of Biochard et al. [1,2,3], an ancestor is either an animal without pedigree information (a founder) or an individual with known pedigree (not a founder) provided it has high contribution to the reference population. The second case refers to animals which are found in pedigree "bottleneck".

The founders (ancestors) with at least 1% gene share in the population were chosen to be reported in the tables, because they contributed in total about 90% (95%) to its gene pool.

RESULTS AND DISCUSSION

The total number of founders for the reference population of 34 animals was 54, and the total number of ancestors was 30. The effective numbers of founders and ancestors were 28 and 16, respectively (Table 1).

Thirty-one animals (14 males and 17 females) were identified as main founders. Among those, 5 individuals (3 dogs and 2 bitches) made the highest gene contribution to the population: from 4% to over 7%. The dog called Czort (KW.T-I306/XXVIII) was the largest contributor (7.38%), closely followed by the dog Wierny (KW.I-188/OP) and the bitch Dolinka (KW.I-189/OP), both with 7.35% contribution. The next two founders, dog Bari z Kotelnicy (PKR.O-LXXII-19853) and bitch Siklawa ze Stoku Gubałówki (KW.T-III-107/XXVIII), accounted for about 4.65% of genes. The gene contributions of 13 founders (6 bitches and 7 dogs) ranged from 2% to 4%, while the rest of the main founders contributed only 1-2% of genes. In total, the 31 main founders contributed nearly 90% of genes to the gene pool of the reference population (Table 2).

The ancestor group with biggest gene contributions included 22 animals (14 males and 8 females). The top 5 ancestors contributed from 6% to ca. 15% of genes. The first place was occupied by the dog named a-Dunajek z Byrtusiowej Płazówki (PKR.I-VIII-1460) who contributed 14.75% of genes. It was followed by the dog Hawrań ze Stoku Gubałówki (PKR.O-CXCVIII-48214) with a contribution of 9.31%, the dog Wierny (KW.I-188/OP) with 7.35%, and the bitches: Dolinka (KW.I-188/OP) with a contribution of 7.35%, and Bystra z Siwej Polany (PKR.I-18235) with 6.78%. The other main ancestors had contributions of up to 5.5%. About 95% of the genetic variability in the reference population can be explained by the contribution of the 22 main ancestors (Table 3).

Eight individuals were found to be both main founders and main ancestors. Their names are printed in italics in Tables 2 and 3.

The results on the effective number of founders (f_e) and ancestors (f_a) of the Tatra Shepherd dog population, obtained in our study, were similar to those reported by Cole et al. [6] for much larger populations of German Shepherd dogs and Labrador Retriever dogs working as guides.

Compared to the values calculated for Tatra Shepherd dogs in the present work, the gene contribution of some founders (almost 16.5%) to the population of Polish hounds assessed by Głażewska [7] was much higher.

In the study of Leroy et al. [13], the f_e and f_a values of 61 dog breeds in France ranged widely: from 10 (Barbets) to 656 (poodles) for f_e, and from 9 to 209 for f_a. The size of the reference population was 112 animals for Barbets, and 8808 animals for poodles. Our results fell in the above range, however, they were estimated for a smaller reference population (only 34 animals).

The effective numbers of founders and ancestors of three breeds of dairy cattle (Holstein, Jersey, and Danish Red) in Denmark [16] were similar to, or much higher than the values determined in our study for Tatra Shepherd dogs, but the reference populations for the cattle breeds were much larger. Higher effective numbers of founders and ancestors were also calculated by Buś and Kania-Gierdziewicz [4] for a Polish Red cattle population, as well as by Kania-Gierdziewicz [10] for Polish Black-and-White bulls. Buś and Kania-Gierdziewicz [4] found that over 95% of the genetic variability in Polish Red cattle was due to 50 main ancestors, the number more than twice as high as the number (22) of main ancestors that accounted for about 95% of the gene pool of the Tatra Shepherd dog population.

The values of f_e and f_a in a population of Arabian horses in Spain [5], markedly bigger (6240 animals) than the population of dogs examined in this paper, were similar to our results, but the gene contributions of chief ancestors were higher (up to 17%). As in our study, Valera et al. [19] investigating the population of Andalusian horses in Spain found the contributions of chief founders to be over 8%, and those of top ancestors to exceed 15%.

Compared to our results, roughly the same values of f_e and f_a were obtained by Zechner et al. [20] in Lipizzaner horses, while lower values: f_e from 18 to 19.5, and f_a from 12 to 13, were calculated by Royo et al. [15] for Black Asturcón ponies. It should be noted that the contribution of the top founder in the latter case exceeded 22%, which was much higher than the highest value for Polish Shepherd dogs.

For Hannover horses, significantly higher f_e and f_a values were reported by Hamann and Distl [9]. In their study, covering a much larger reference population, the contributions of the top 15 founders and ancestors to the population gene pool, below 5.5% for stallions and below 1% for mares, were markedly lower than our results. Higher effective numbers of founders and ancestors were also determined by Gutiérrez et al. [8] for a population of Catalonian donkeys in Spain.

CONCLUSIONS

The effective number of founders for the reference population of 34 Tatra Shepherd dogs was 28. The effective number of ancestors (16) was lower, which suggests that there might have been one or more population bottlenecks.

The number of founders with the largest gene contributions (over 1%) to the reference population of Tatra Shepherd dogs was 31, among them 14 males and 17 females.

The contributions of the 31 main founders accounted for about 90% of the gene pool of the reference population under study.

Twenty-two animals (14 dogs and 8 bitches) formed the group of ancestors that contributed most to the population gene pool. Their contributions explained about 95% of the genetic variability of the Tatra Shepherd dog reference population.

Eight individuals were both top founders and top ancestors.

ACKNOWLEDGEMENTS

The authors thank all the Tatra Shepherd dog breeders registered in the Krakow Branch of the Polish Kennel Club for providing access to their animals' pedigrees.

REFERENCES

1. Boichard D., Maignel L., Verrier E., 1995. Estimation of the effective number of a population from pedigree information. 2nd European Workshop on Advanced Biometrical Methods in Animal Breeding, Salzburg, Austria.

2. Boichard D., Maignel L., Verrier E., 1996. Analyse généalogique des races bovines laitières françaises. INRA Productions Animales, 9(5), 323–335.

3. Boichard D., Maignel L., Verrier E., 1997. The value of using probabilities of gene origin to measure genetic variability in a population. Genetics Selection Evolution, 29, 5–23.

4. Buś M., Kania-Gierdziewicz J., 2000. Genetic variability in Polish Red cattle population. Roczniki Naukowe Zootechniki, 27(4), 29–41.

5. Cervantes I., Molina A., Goyache F., Gutiérrez J. P., Valera M., 2008. Population history and genetic variability in the Spanish Arab Horse assessed via pedigree analysis. Livestock Science, 113, 24–33.

6. Cole J. B., Franke D. E., Leighton E. A., 2004. Population structure of a colony of dog guides. Journal of Animal Science, 82, 2906–2912.

7. Głażewska I., 2008. Genetic diversity in Polish hounds estimated by pedigree analysis. Livestock Science, 113, 296–301.

8. Gutiérrez J. P., Marmi J., Goyache F., Jordana J., 2005. Pedigree information reveals moderate to high levels of inbreeding and a weak population structure in the endangered Catalonian donkey breed. Journal of Animal Breeding and Genetics, 122, 378–386.

9. Haman H., Distl O., 2008. Genetic variability in Hanoverian warmblood horses using pedigree analysis. Journal of Animal Science, 86, 1503–1513.

10. Kania-Gierdziewicz J., 2003. Efektywna liczba założycieli krajowej populacji buhajów czarno-białych [Effective number of founders of Polish Black-and-White bull population]. Zeszyty Naukowe Polskiego Towarzystwa Zootechnicznego, Przegląd Hodowlany, 68(1), 167–174 [in Polish].

11. Lacy R. C., 1989. Analysis of Founder Representation in Pedigrees: Founder Equivalents and Founder Genome Equivalents. Zoo Biology, 8, 111–123.

12. Lacy R. C., 1995. Clarification of Genetic Terms and Their Use in the Management of Captive Populations. Zoo Biology, 14, 565–578.

13. Leroy G., Verrier E., Meriaux J. C., Rognon X., 2009. Genetic diversity of dog breeds: within-breed diversity comparing genealogical and molecular data. Animal Genetics, doi:10.1111/j/1365–2052.2008.01842.x

14. Redlicka A., Redlicki M., 2003. Owczarek podhalański [Tatra Shepherd dog]. Agencja Wyd. MAKO PRESS, Warszawa[in Polish].

15. Royo L. J., Álvarez I., Gutiérrez J. P., Fernández I., Goyache F., 2007. Genetic variability in the endangered Asturcón pony assessed using genealogical and molecular information. Livestock Science, 107, 162–169.

16. Sørensen A. C., Sørensen M. K., Berg P., 2005. Inbreeding in Danish dairy cattle breeds. Journal of Dairy Science, 88, 1865–1872.

17. Ściesiński K., 2002a. Charakterystyka współczesnej populacji owczarka podhalańskiego (cz.I) [Characteristics of contemporary Tatra Shepherd dog population (part I)]. Przegląd Hodowlany, 6, 25–28 [in Polish].

18. Ściesiński K., 2002b. Charakterystyka współczesnej populacji owczarka podhalańskiego (cz.II) [Characteristics of contemporary Tatra Shepherd dog population (part II)].Przegląd Hodowlany, 7, 20–25 [in Polish].

19. Valera M., Molina A., Gutiérrez J. P., Gómez J., Goyache F., 2005. Pedigree analysis in the Andalusian horse: population structure, genetic variability and influence of the Carthusian strain. Livestock Production Science, 95, 57–66.

20. Zechner P., Sölkner J., Bodo I., Druml T., Baumung R., Achmann R., Marti E., Habe F., Brem G., 2002. Analysis of diversity and population structure in the Lipizzan horse breed based on pedigree information. Livestock Production Science, 77, 137–146.

Accepted for print: 23.06.2010

Responses to this article, comments are invited and should be submitted within three months of the publication of the article. If accepted for publication, they will be published in the chapter headed 'Discussions' and hyperlinked to the article.