Towards Genetically Informed Conservation of the Bardoka and Karakachan Sheep Breeds Autochthonous to Serbia

Bardoka and Karakachan sheep are primitive regional transboundary Pramenka-type sheep autochthonous to the Balkan Peninsula, whose populations have been reduced to a critically small size in Serbia. We genotyped 105 Bardoka animals (97 ewes and 8 rams from three flocks) and 97 Karakachan sheep (86 ewes and 11 rams from four flocks), along with 28 Ile-de-France (IDF) animals used for a comparison (25 ewes and 3 rams), using 14 nuclear microsatellites to assess their genetic status and establish a foundation for their genetically informed conservation. We utilized genetic data to assess inbreeding values of individuals (I) and pairwise relatedness (r) traditionally inferred from the pedigree data, which are incomplete in the studied autochthonous breeds. We used these data to assemble a data set of unrelated individuals for subsequent genetic analyses. Low but statistically significant genetic differentiation of Bardoka and Karakachan sheep (FST = 0.031, p < 0.01) demonstrates that these phenotypically distinct breeds differ at the genetic level as well. The I and r in ewes were higher in the Karakachan sheep (I = 0.09, r = 0.07) than in Bardoka (I = 0.06, r = 0.06). Contrary to the IDF rams, Bardoka and Karakachan sheep rams were genetically heterogeneous and those of the latter breed displayed higher average r values (0.01 vs. 0.08, respectively). Rams of both local breeds had identical I values of 0.02. Although Bardoka and Karakachan sheep still harbor rather high levels of genetic diversity (HE = 0.761 ± 0.028 and 0.761 ± 0.021, respectively), the overall genetic data demonstrate that the genetic consequences of the population decline were more severe in the latter breed. A genetic structure presenting a general trend of differentiation of flocks with low genetic exchange into separate genetic entities was observed, indicating the effects of genetic drift. The implementation of the genetically informed conservation, together with the ongoing efforts of the state to enlarge the Bardoka and Karakachan sheep ...