Analysis of Genetic Variability in the Argentine Polo Horse With a Panel of Microsatellite Markers.

This research investigates the genetic diversity in Argentine Polo horses over a 16-year period. It found that the use of assisted reproduction technologies and intensive selection based on sporting performance may have had an impact on the breed’s genetic variability.

Objective of Research

• The research was aimed at studying the impact of assisted breeding technologies, an open registry policy, and performance-based selection on the genetic variability of the Argentine Polo breed over a period of 16 years.

Method of Study

• The scientists used a parentage panel of between 11 and 15 microsatellite markers to monitor potential changes in allele frequencies, heterozygosity (a measure of genetic variation), and exclusion probability (measures the chance that a tested parent is the biological parent of the offspring).

Findings and Analysis

• The study discovered that the frequency of 36 alleles (alternate variants of a gene that arise by mutation) in 13 markers exhibited significant deviation from the projected changes due to random genetic drift. This suggests that changes were not just due to natural genetic variation but could be as a result of human breeding interventions.
• In addition, six markers showed both an increase in allele frequency and a decrease in expected heterozygosity. The latter suggests that a decrease in the overall genetic diversity in the population, potentially due to selective breeding, or “hitchhiking” effects – where certain genes get passed on together more frequently than would be expected by chance.
• The research also found a significant reduction in the average expected heterozygosity, although it was still lower than the observed heterozygosity, suggesting a relatively low level of inbreeding.
• The exclusion probability of the panel showed a trend to decrease but remained over 0.9995, exceeding the recommended value for equine parentage exclusion. This indicates a high probability that the tested parent is not the biological parent of the offspring and can be confidently excluded.

Conclusion

• The overall conclusion of the study is that assisted reproduction technologies and selection practices based on sporting performance have influenced the genetic variability in the Argentine Polo horse breed over the 16-year period of the study.