Population Structure Analysis of the Border Collie Dog Breed in Hungary

SIMPLE SUMMARY: The appearance of dog breeds is constantly changing, for many reasons. The Border Collie breed has several lines depending on sport, show, or work requirements, with closed breeding practices within these lines in recent decades. The aim of the study was to map the current population in Hungary and determine the possible inbreeding levels in and between the different subpopulations. The main finding of the study was that there is a detectable genetic divergence between the show and working line. In addition, genetic variability within the breed is decreasing due to a lack of suitable mating plans and the education of the breeders who are repeatedly choosing to breed animals with similar show-related characteristics. The size of the active breeding population has decreased dramatically in the past years. However, there are many dogs in the country without a pedigree. It can be seen that despite the proportion of registered breeders, dog owners prefer not to buy purebred dogs, and thus most of the pups born in Hungary are exported to other countries. ABSTRACT: Pedigree data of the Border Collie dog breed were collected in Hungary to examine genetic diversity within the breed and its different lines. The database was based on available herd books dating from the development of the breed (in the late 1800s) to the present day. The constructed pedigree file consisted of 13,339 individuals, of which 1566 dogs (born between 2010 and 2016) composed the alive reference population which was active from breeding perspective. The breed is subdivided by phenotype, showing a thicker coat, harmonic movement, a wide skull, and heavier bones for the show type, and a thinner or sometimes short coat and smaller body for the working line, while the mixed line is quite heterogeneous (a combination of the above). Thus, the reference population was dissected according to the existing lines. The number of founders was 894, but eight individuals were responsible for contributing 50% of the genetic variability. The reference population had a pedigree completeness of 99.6% up to 15 generations and an inbreeding coefficient of 9.86%. Due to the changing breed standards and the requirements of the potential buyers, the effective population size substantially decreased between 2010 and 2016. Generation intervals varied between 4.09 and 4.71 years, where the sire paths were longer due to the later initial age of breeding in males compared to females. Genetic differences among the existing lines calculated by fixation indices are not significant; nonetheless ancestral inbreeding coefficients are able to show contrasts.