The legacy of Columbus in American horse populations assessed by microsatellite markers.

The research investigates the genetic links and ancestry of the Criollo horse populations across the Americas, tracing their origins back to horses brought from the Iberian Peninsula during colonization in the 15th to 17th century. Breeds from 12 American countries, the Iberian Peninsula, France, Morocco, and also Thoroughbred and Arabian cosmopolitan horses were studied using genotyping of 25 autosomal microsatellites.

Research Methodology

• For their study, the researchers performed genotyping on 25 autosomal microsatellites from 50 horse breeds. This included Criollo populations from 12 American countries (27 breeds), breeds from the Iberian Peninsula (19), one breed each from France and Morocco, and two cosmopolitan horse breeds – the Thoroughbred and Arabian.
• The 25 autosomal microsatellites are a set of specific repetitive DNA sequences that scientists use to study genetic diversity. They are highly variable and provide a detailed fingerprint of an organism’s genetic makeup.

Findings

• Based on their genetic relationships, the breeds fell into five clusters: the Celtic, Iberian, North American with Thoroughbred influence, most Colombian breeds, and almost all other Criollo breeds.
• The group labeled “all other Criollo breeds” exhibited the closest genetic relationship with breeds originating from the Iberian Peninsula, particularly the Celtic group.
• The analysis revealed that other breeds contributed approximately 50%, 30%, and 20% of the genetic makeup for the entire set of Criollo breeds, and these contributions largely came from the Celtic, Iberian, and Arab-Thoroughbred groups, respectively.

Significance and Implications

• The locations with the greatest genetic diversity, or hotspots, were found in populations from Colombia, Ecuador, Brazil, Paraguay, and the western United States. Accordingly, these regions may indicate points of arrival and dispersion of Criollo horses in the American continent.
• The results of the study suggest that despite sharing a common ancestry, each Criollo breed maintains its own unique genetic identity. This understanding could inform future breeding programs and conservation efforts for these horse populations.