GENETIC STRUCTURE ANALYSIS OF TATRA SHEPHERD DOG POPULATION IN AREA OF KRAKOW BRANCH OF POLISH KENNEL CLUB
I. INBREEDING AND RELATIONSHIP COEFFICIENTS

Bożena Kalinowska¹, Maciej Gierdziewicz², Joanna Kania-Gierdziewicz^2
1 Department of Swine and Small Ruminant Breeding, University of Agriculture, Cracow, Poland
² Department of Genetics and Animal Breeding, University of Agriculture, Cracow, Poland

ABSTRACT

The study investigates inbreeding and relationship in the 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 coefficients of inbreeding (F_X) were estimated for all 150 animals and for each sex separately, and the coefficients of relationship (R_XY) were calculated for all animals, for each sex separately, and for dogs and bitches. Among all the animals, 23.33% were inbred; about 50% of those belonged to the active population. The proportion of inbred individuals was 27.27% for males and 20.24% for females. The F_X values for all animals and for inbred individuals were 1.37% and 5.85%, respectively. In the sex groups, F_X averaged 1.76% and 1.06% for all dogs and all bitches, and 6.64%, 5.23% for inbred dogs and inbred bitches. In the population under study, 35.55% of pairs of individuals were related. The average values of R_XY for all and related pairs were 5.19% and 14.59%, respectively. In males, 41.03% pairs were related, with R_XY for all and inbred dogs averaging 6.12% and 14.92%, respectively. In females, those values were slightly lower: 31.24% related pairs; R_XY averaging 4.53% and 14.51% for all and related pairs, respectively. Only 36.15% of mixed male-female pairs were related; the R_XY values averaged 5.24% and 14.49,% respectively, for all and related pairs.

Key words: genetic structure, inbreeding, relationship, Tatra Shepherd dog.

INTRODUCTION

The Tatra Shepherd dog is a Polish native breed that has been bred in the mountain region of Zakopane. As the Tatra Mountains form a state border, these dogs have lived in isolation from those in Slovakia. In 1937, two organizations: the Polish Association of Pedigree Dog Breeders and the Society of Working Dog Breeders organized the first dog show for Tatra Shepherds. This event became a starting point for breeding the Tatra Shepherd dog in Zakopane. Owing to the fact that many shepherds kept those dogs in Zakopane during World War II, the breed managed to survive in its native areas. After the war, when the Polish Kennel Club (PKC) was reestablished, Prof. T. Marchlewski organized shows for Tatra Shepherd dogs in Krakow [1,22].

In the Zakopane Branch of PKC, Dr H. Dereziński had been searching for typical dogs to be bred in mountains, and managed to find 120 dogs for the first post-war show held in 1954. The fact that the Tatra Shepherd dog still appears at dog shows is due to his hard work for many years. Nowadays, the breed representatives are very limited in number, and breeding problems connected with the small size of population begin to occur [23].

The aim of this work was to estimate inbreeding and relationship coefficients in the population of 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 to obtain additive relationship matrix of the dogs and their 116 ancestors, altogether 150 animals. The coefficients of inbreeding (F_X) and relationship (R_XY) were calculated according to the recursive Tier [24] algorithm modified by Gierdziewicz and Kania-Gierdziewicz [5]. The relationship coefficients were analyzed among all the 150 animals i.e. for all 11175 possible pairs, for each sex separately (2145 pairs "dog-dog" and 3486 pairs "bitch-bitch"), and between dogs and bitches (5544 pairs).

RESULTS AND DISCUSSION

Among the 150 animals considered in the study, 35 individuals (23.33%) were inbred; about 50% of those belonged to the active population. The F_X values for all the animals and for inbred individuals were 1.37% and 5.85%, respectively. The group of 66 males comprised 18 (27.27%) inbred individuals, and the group of 84 females has 17 (20.24%) inbred ones. The average values of F_X were 1.76% and 1.06%,  respectively, for all dogs and all bitches, and 6.64%, 5.23% for inbred dogs and inbred bitches (Table 1). For 34 active animals, the average inbreeding coefficient value was about 2.96%.

Similar results were obtained by Drozd and Karpiński [4] for a population of Rottweilers whose size, however, was remarkably larger than that of TS dogs in our study (483 vs. 150). For other breeds, the values of F_X were much lower than our results and did not exceed 1%. The corresponding values for inbred animals ranged from about 2% in German Shepherd bitches to almost 9% in German Mastiff males [4]. Hence, the inbreeding coefficients of Tatra Shepherd dogs in our study were lower than in German Mastiffs and much higher than in German Shepherds.

Jakubczak and Jeżewska [11], who examined the level of inbreeding and its influence on reproductive and breeding performance in the pastel fox, reported similar or lower F_X values.

By contrast, Cole et al. [3], who examined populations of German Shepherds and Labrador Retrievers working as guide dogs, found the average value of F_X to be about 25% for the former, and around 15% for the latter.

A higher level of inbreeding was detected in a small population of Polish hounds studied by Głażewska [8]: the average F_X increased with time to reach the value of 30-40%, which resulted in reproduction and health problems.

The results achieved by Ólafsdóttir and Kristjánsson [16] for a small population of Iceland Sheepdog, being currently at the brink of extinction, roughly followed the above pattern. The authors estimated the average F_X at 21%, and suggested that frequent cases of hip dysplasia occurring in these dogs may be attributed to this inbreeding level.

On the other hand, the inbreeding coefficients of 61 dog breeds in France studied by Leroy et al. [13] ranged from near zero (0.3% for Romagna Water dog) to over 8% (8.8% in Berger des Pyrénées – Pyrenean Shepherd) – the last value exceeding our results significantly.

The same or lower values of F_X were reported by Sørensen et al. [19] for three cattle breeds in Denmark: from 1.4% (Danish Red) to 3.9% (Holsteins); by Kania-Gierdziewicz [12] for Polish Black-and-White bulls – about 0.3% (this time the value was much lower); by Mrode et al. [15] for Holstein cows in Great Britain, Italy and Ireland – from near zero to about 2.5%; and by Li et al. [14] for Finnish sheep.

Cervantes et al. [2] who examined a population of Arabian horses in Spain recorded higher inbreeding coefficients than those obtained in this study: the average F_X value for the whole population was 7%, and for youngest animals it exceeded 26%. Similarly, higher average values were calculated by Głażewska [6] as well as Głażewska and Jezierski [7] for Polish Arabian horses.

The inbreeding level of almost 20% was found by Sevinga et al. [18] in Dutch Friesian horses, by Valera et al. [25] in Andalusian breed, and by Zechner et al. [26] in Lipizzaner horses.

The F_X values which were almost the same or slightly higher than those from our study were reported by Royo et al. [17] for a small population of Asturcón ponies, by Hamman and Distl [10] for Hanoverian warmblood horses, and by Gutiérrez et al. [9] for the endangered population of Catalonian donkeys in Spain. The values similar to ours were also calculated by Sternicki et al. [20] for David's deer, and by Szablewski and Szwaczkowski [21] for zoological garden populations of Przewalski's horse, Arabian oryx and David's deer.

Table 2 shows a list of inbred animals from the Tatra Shepherd (TS) dog population. Those with highest inbreeding coefficients were dogs: Bari z Mroźnej Dujawicy (PKR.I-36094) whose F_X exceeded 14% (the exact value was 14.06%), followed by a-Dunajek z Byrtusiowej Płazówki (PKR.I-VIII-1460) with F_X = 12.50%, and two dogs – Japa Niedźwiedzia Łapa (PKR.I-54757) and Baciar z Zadymy (PKR.I-25555) with F_X over 10%. The next positions were occupied by bitches: two sisters – Garda z Zadymy (PKR.I-35458) and Gloria z Zadymy (PKR.I-35044), and an older bitch Buksa z Zadymy (PKR.I-25855) whose name appears in many pedigrees of TS dogs; all three with F_X over 10%, highest among females. The third female had the same parents but came from a different litter.

The TS dog population included 11175 pairs, 3973 (35.55%) of which were related. The relationship coefficients for all pairs and related pairs amounted to 5.19% and 14.59%, respectively. Among the 2145 pairs of males, there were only 880 (41.03%) related pairs. The average R_XY values for this group were 6.12% and 14.92%, respectively, for all pairs and related pairs. Among the 3486 pairs of females, 1089 (31.24%) related pairs were identified, with the average R_XY values of 4.53% and 14.51%, respectively, for all pairs and related pairs. For the total number of 5544 mixed dog-bitch pairs, only 2004 (36.15%) were related. The R_XY coefficient in this group had the respective values of 5.24% and 14.49% for all pairs and related pairs (Table 3).

To compare, Drozd and Karpiński [4] got much lower values of R_XY, merely 1%, in four dog breeds. The values calculated by Leroy et al. [13] for 61 dog breeds in France were similar to our results, whereas those obtained by Cole et al. [3] for German Shepherds and Labrador Retrievers were the same or much higher (about 25%).

Significantly lower R_XY values in related pairs were found by Kania-Gierdziewicz [12] in Polish Black-and-White bulls (about 2.5%), and by Li et al. [14] in Finnish sheep (not more than 2%). More diversed R_XY values as those computed in our study, ranging from about 1% to almost 11%, were calculated by Mrode et al. [15] for Holstein cows.

Similarly, Arabian horses bred in Spain [2], and in Poland [7] proved to be less related than the Tatra Shepherd dogs described in this paper. On the other hand, Andalusian horses exhibited much higher relationship coefficients (about 12% to 15%) [25] than the TS dogs did. Also Lipizzaner horses were also more related to one another [26], with the R_XY coefficients ranging from 11.5 to over 16%.

Other studies conducted by Royo et al. [17] with black Asturcón ponies, and by Gutiérrez et al. [9] with Catalonian donkeys resulted in the values of relationship coefficients similar to, or slightly higher than those obtained in our study.

CONCLUSIONS

In the Tatra Shepherd dog population under study, over 23% individuals were inbred; non-zero inbreeding coefficients were found for about 27% dogs and slightly more than 20% bitches.

The average inbreeding coefficient was 1.37% for all the animals and 5.85% for inbred ones; such a level does not pose danger to the population. However, detailed analysis revealed that some individuals exhibited high values of F_X.

About half of the dogs and bitches in the active population were inbred.

The highest inbreeding coefficient was 14.06% (for the dog Bari z Mroźnej Dujawicy, PKR.I.-36094), and the highest relationship coefficient was 60%.

Related animal pairs had an average relationship coefficient of about 14–15%.

Due to a small size of the population under study, it would be useful to extend the research to the whole population of Tatra Shepherd dogs in Poland, and even to include the animals from abroad.

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.

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Accepted for print: 23.06.2010

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