[Genetic differentiation between breeds of horses by polymorphic blood protein loci].

This paper investigates the genetic differentiation of 27 horse breeds, primarily from the USSR, based on differences in serum proteins. The research reveals higher genetic variability among native breeds compared to cultured ones and acknowledges the distinct genetic composition of certain breeds like the Przewalski’s Horse due to specific breeding history and selection pressures.

Breed Differentiation Based on Serum Proteins Polymorphism

• The study focused on 27 horse breeds, most of which originated in the USSR. These breeds were examined for genetic differentiation using serum proteins polymorphism, specifically looking at the Tf, Al, Es loci. This approach helps understand the genetic distinctiveness and relatedness among the horse breeds.
• Polymorphism, in this context, relates to the occurrence of different forms, or alleles, within the same population. The Tf, Al, Es loci are specific points on a chromosome, each corresponding to a particular gene responsible for encoding different types of serum proteins.

Genetic Variability and Breed Origin

• The researchers found higher genetic variability among aborigine or native breeds compared to the cultural (or selectively bred) ones. This may be due to the fact that native breeds have had more opportunity for genetic mixing and less selective pressure as compared to bred horses.
• The Przewalski’s Horse, for instance, showed significant genetic erosion, which was attributed to a unique history of this population and the lower number of individual horses analyzed. The reduced gene pool signifies higher uniformity and lesser variability in their genetic makeup.

Genetic Distances and Intensity of Breeding

• The genetic distances among breed types served as an indicator of the direction and intensity of breeding. Bigger distance means more genetic variations, making a breed genetically distinct from another.
• Notably, the researchers found high genetic distances between the Przewalski’s Horse, Shetland Pony, and other horses, illustrating the impact of selective breeding or the “bottle neck” effect on their genetics.

Genetic Clustering of USSR Horse Breeds

• The findings showed that 9 native breeds from the USSR clustered into one group, setting them apart from foreign horse breeds. This clustering indicates a unique gene pool that sets these breeds apart from their global counterparts.
• This genetic specificity contributes to biodiversity and holds relevance for maintaining genetic health and resistance among horse populations. It could also be significant for conservation and breeding policy decisions in the future.