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

Carmen Marín Navas,Antonio ,Francisco Javier Navas González,José Manuel León Jurado,Amy Katherine Mclean,Juan Vicente Delgado Bermejo

doi:10.3390/ani11020269

Abstract

Simple SummaryThe demographic and genetic diversity structure and the contributions of Spanish (PRE) and Arabian Purebred (PRá) horses to the process of conformation of the Hispano-Arabian (Há) horse breed were evaluated. Genetic diversity parameters (inbreeding coefficient, genetic conservation index, coancestry coefficient, non-random mating degree, relatedness coefficient, maximum, complete, and equivalent generations, and number of offspring) were evaluated using a discriminant canonical analysis to determine the partial contributions of each founder breed to the development of Há horse breed. The calculation of Nei genetic distances suggests the overlapping could be estimated in 29.55% of the gene pool of the Há having a PRE origin while 70.45% of the gene pool of the breed may derive from a PRá origin. Although a progressive loss of founder representation may have occurred, breeding strategies implemented considering mating between animals with the highest genetic conservation indices (GCI) may compensate for its effects.Genetic diversity and population structure were analyzed using the historical and current pedigree information of the Arabian (PRá), Spanish Purebred (PRE), and Hispano-Arabian (Há) 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 Há 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 Há breed, which is more closely genetically related to PRá 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 PRá, PRE, and Há, 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 PRá, PRE, and Há is 6%, 7%, and 4%, respectively).

Highlights

The prospects of complementing already established endangered breeds or populations into a multi-breed composite population was proposed by Shrestha [1]
Since the Hispano-Arabian (Há) horse breed is the product that results from the cross between the Spanish (PRE) and Arabian (PRá) purebred horses, the historical pedigree files for the three breeds were considered to build the historical pedigree database used in this study
The historical number of births was noticeably higher in PRE horses when compared to PRá horses and Há horses [60,61]

Summary

Introduction

The prospects of complementing already established endangered breeds or populations into a multi-breed composite population was proposed by Shrestha [1]. As a result of this introduction, even though a small number of pure Arabian horses (PRá) were brought by the army of Baly , they were sufficient to originate a new type of horse: the Iberian Arabian horse. These PRá horses from Spain crossed with the primitive Spanish horse, found in the peninsula, originated the predecessors of the current Há horse [4]

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