Relationship of Genetic Connectedness Among Flocks with Effective Population Size in Dairy-Oriented Pag Sheep

Development of any trait-directed selection strategy requires basic knowledge about some important population-specific parameters such as the effective population size N e and genetic connectedness among flocks. The N e , as an indirect measure of genetic variability, is important for the conservation of the genome, while genetic connectedness is necessary for unbiased across-flock genetic evaluation. The average number of full generations (NFG) in the reference population of the Pag sheep under selection for dairy traits was 3.05. The N e estimated from individual coancestry rate ∆ C i j in the last generation was 127 animals, and the average prediction error variance of the difference in EBVs between animals belonging to different flocks ( P E V D i ′ , j ′ ¯ ) was 0.81. Although conceptually different, these two population genetic parameters may be related in the populations under selection. Although it is difficult to prove this hypothesis, we decided to test it by regressing the partial (generational) estimates of N e on P E V D i ′ , j ′ ¯ . It was estimated that ∆ P E V D i ′ , j ′ ¯ of −0.01 was accompanied by ∆ N e of +5.5 animals. The results suggest that strengthening genetic connectedness among flocks in populations might have a positive impact on genetic diversity; however, more research is needed before generalization.