Genetic diversity and structure of 2 indigenous sheep breeds (Kotel and Teteven) in Bulgaria using microsatellite markers

This study analyzed the genetic diversity and structure of two Bulgarian indigenous sheep (Ovis aries) breeds – Kotel and Teteven, each presented by 4 flocks, using 15 microsatellite markers. A total of 195 alleles were identified. Among the markers used, the most informative were INRA5 and OarFCB20 with PIC values of 0.87. Both breeds showed a high level of genetic diversity with average values of He and Ho, respectively 0.74 and 0.76. The observed high level of genetic diversity is combined with the absence of heterozygous deficiency reported as Fis values of 0.04 and 0.07, respectively for Kotel and Teteven breeds. Low level of genetic differentiation between the two breeds was observed, as evidenced by the low value of Fst of 0.09, and analysis of variance (ANOVA) data showing that only 9% of the total variation is due to variation between breeds, whereas 91% is due to variation within breeds. Furthermore, we revealed a breeding practice that comprises an exchange of animals between the breeds which reflects in the clustering obtained by STRUCTURE analysis. According to it, Kotel breed is a more homogenous population and forms cluster 1, whereas Teteven breed is more heterogenous and consists of two subpopulations that form two distinct clusters. The results obtained in the present study confirm the high potential of microsatellite markers in studies related to both breed affiliation and purity and can serve as a basis for the implementation of future management and conservation programs of these indigenous breeds.