Discriminant Canonical Analysis of the Contribution of Spanish and Arabian Purebred Horses to the Genetic Diversity and Population Structure of Hispano-Arabian Horses.

Genetic diversity and population structure were analyzed using the historical and current pedigree information of the Arabian (PRa), Spanish Purebred (PRE), and Hispano-Arabian (Ha) horse breeds. Genetic diversity parameters were computed and a canonical discriminant analysis was used to determine the contributions of ancestor breeds to the genetic diversity of the Ha horse. Pedigree records were available for 207,100 animals born between 1884 and 2019. Nei's distances and the equivalent subpopulations number indicated the existence of a highly structured, integrated population for the Ha breed, which is more closely genetically related to PRa than PRE horses. An increase in the length of the generation interval might be an effective solution to reduce the increase in inbreeding found in the studied breeds (8.44%, 8.50%, and 2.89%, for PRa, PRE, and Ha, respectively). Wright's fixation statistics indicated slight interherd inbreeding. Pedigree completeness suggested genetic parameters were highly reliable. High GCI levels found for number of founders and non-founders and their relationship to the evolution of inbreeding permit controlling potential deleterious negative effects from excessively frequent mating between interrelated individuals. For instance, the use of individuals presenting high GCI may balance founders' gene contributions and consequently preserve genetic diversity levels (current genetic diversity loss in PRa, PRE, and Ha is 6%, 7%, and 4%, respectively).