Phylogenetic relationships of Argentinean Creole horses and other South American and Spanish breeds inferred from mitochondrial DNA sequences.

The research aims to understand the genetic relationships between Argentinean Creole horses and other South American and Spanish breeds through the analysis of mitochondrial DNA sequences. The study highlights a high level of variability both within and among breeds, with evidence of shared haplotypes, although no distinct phylogenetic groups are seen.

Research Methodology

• The researchers analyzed a portion of the mitochondrial D-loop of 104 animals. These belonged to nine South American and Spanish breeds.
• The analysis methods used were Single Strand Conformational Polymorphism (SSCP) and DNA sequencing. SSCP allows for the detection of genetic variations, while DNA sequencing determines the order of nucleotides in a DNA molecule.

Research Findings

• The study recognized a high degree of variability both within and between breeds. Out of the total sequences obtained, 61 positions were polymorphic, equating to 16% of the total.
• The average divergence between any pair of DNA sequences was observed at 2.8%.
• Argentinean Creole horses were found to share two haplotypes (distinct variations on a genetic locus or chromosome) with the Peruvian Paso breed from Argentina. Furthermore, the most common haplotype of Argentinean Creole horses matched one found in Andalusian horses.

Interpretation and Conclusion

• Despite substantial differentiation among breeds, indicated by a significant Wright’s Fixation Index (FST), no clearly defined phylogenetic (evolutionary) groups were observed among the breeds. This suggests a lack of clear evolutionary relationships between South American and the other horse breeds analyzed.
• While these findings could point towards a mixed ancestry of South American breeds in relation to Spanish breeds, the authors propose an alternate interpretation. They suggest that the results likely indicate the preservation of very old maternal lineages within the breeds analyzed.

Overall, this study contributes to our understanding of the genetic diversity and ancestry of various horse breeds, with a specific focus on South American and Spanish breeds. This information can be useful for breed conservation efforts and provides valuable insights into horse breed evolution.