Morphological and genetic diversity of Pura Raza Español horse with regard to the coat colour.

This study researched the link between certain gene mutations that determine coat color and their physiological and behavioral effects on the Pura Raza Español (PRE) horse, identifying clear differences among four distinct subpopulations: grey, bay, chestnut and black.

Morphological and Genetic Analysis by Coat Colour

• The researchers conducted an analysis of both physical characteristics (morphological traits) and genetic data of the Pura Raza Español (PRE) horse.
• They established four separate subpopulations according to coat color, which are grey, bay, chestnut, and black. Each of these colors were found to show significant correlation with morphological measurements such as body size, shape, and structure.
• Among the four subgroups, the grey-coated subgroup presented the lowest observed and expected levels of gene diversity (heterozygosity), suggesting unique original variants or ancestral alleles. These may have occurred due to genetic drift, a random change in gene frequencies, and selection pressures.

Population Divergence and Gene Flow

• The study found that among the four groupings based on coat color, the grey-coated horses are the most genetically distinct.
• The grey horses demonstrated the lowest gene flow, which measures the exchange and mixing of genes between populations. This would indicate less breeding with horses of other coat colors.
• Assessments of divergence times using average square distance calculations suggested that the grey horses may have been the original population of PRE horses, from which the bay, chestnut, and black subpopulations diverged.

The Pleiotropic Effect and Coat Colour

• The differences in physical characteristics and genetic structure between the coat color subpopulations indicate a possible pleiotropic effect. Pleiotropy refers to a single gene affecting more than one trait. In this case, the same genes that determine coat color in PRE horses might also impact other physiological and behavioral traits.
• Highly similar genetic structure was observed between the bay and chestnut PRE horses, while clear differences in morphological traits were evident between grey and chestnut mares.
• The study concludes by stating that further research is needed, incorporating more genomic information, to fully understand the mechanisms driving these observations.