Genetic variability in local Brazilian horse lines using microsatellite markers.

The research focuses on evaluating genetic variability in different Brazilian horse breeds using microsatellite markers. The study identifies significant genetic distinctiveness within the breeds which suggests the need for their preservation due to their unique genetic traits.

Methodology

• The researchers analyzed the genetic variability of five naturalized or local Brazilian horse breeds – Campeira, Lavradeira, Pantaneira, Mangalarga Marchador and the genetic group Baixadeiro, and two exotic breeds – English Thoroughbred and Arab.
• They used 11 microsatellite markers for this purpose and collected blood samples from 328 horses representing these breeds.

Findings

• The study discovered substantial genetic variability between these microsatellite loci. The observed heterozygosis fluctuated between 0.426 and 0.768 while polymorphism information content values ranged between 0.751 and 0.914.
• All the breeds displayed high inbreeding coefficients and were not in Hardy-Weinberg equilibrium, signifying that their genetic structure does not reflect random mating or is influenced by other evolutionary forces.
• The smallest genetic distance was seen between the Pantaneira and Arab breeds, indicating a certain level of genetic similarity or shared ancestry between these breeds.

Implications

• The principal component analyses and Bayesian approach demonstrated the exotic breeds, specifically the English Thoroughbred and Arab, have significantly influenced the genetic composition of the local breeds.
• It was also shown these exotic breeds have been introgressed into the Pantaneira and Lavradeira breeds, and there was a distinct genetic proximity between the Arab, Pantaneira and Mangalarga Marchador populations.
• The study stresses that centuries of natural selection in Brazil make these local breeds genetically unique, calling for the need to conserve these unique genetic attributes.
• This uniqueness suggests a reduced gene flow between these different breeds, which means they have evolved distinctly with limited mixing of genes, making them genetically distinctive.
• The results advocate for the inclusion of these horse breeds in animal genetic resource conservation programs to maximize their genetic variability and to conserve useful allele combinations that can be utilized in future breeding programs.