Assessment of population structure depending on breeding objectives in Spanish Arabian horse by genealogical and molecular information

The Arabian Horse is one of the most valued breeds in an international and historical context and has been involved in the formation of many other horse breeds. Since 2005, the Spanish Arabian Horse Breeder Association (AECCA) has developed a breeding program aimed at improving both conformation traits and endurance performance. While this selection depends on individual breeders, a population structure might appear by preferential mating within groups of animals according to different objectives. The aims of this study were to determine the differences between Arabian horses bred for different breeding objectives: endurance competitions, morphological shows and other aptitudes and to check if this structure population can be assessed by using genealogical, molecular tools or both. Genealogical and molecular information was randomly obtained from 120 Arabian horses. The animals were classified into three groups according to the breeding goal: morphology, endurance and other aptitudes. Some initial analyses were carried out to study the structure of the sampled animals using genealogical and molecular parameters. An analysis of the genetic structure using both types of information source was performed. Both molecular and genealogical analyses were congruent, and both seemed to be valid when studying the genetic structure of this population. The correlation between coancestries using molecular and pedigree information was 0.60. The differences between the groups were minimum when compared with the genetic structure within groups. Therefore, a horse with a specific breeding objective is not genetically much different regard the rest of the objectives. However, the morphological group appeared as the most separated from the rest, both at a genealogical and molecular level. Regarding the possible impact of the subdivision in the population it can be claimed that no loss of genetic variability is expected in the short-term, because the groups were genetically