Greater genetic variability in Argentine Creole than in Thoroughbred horses based on serum protein polymorphisms.

This research investigates the genetic polymorphism of five blood proteins in two different breeds of horses: the Thoroughbred and the Argentine Creole. The study found a higher degree of genetic variability in Argentine Creoles, which may be due to natural selection. In contrast, the Thoroughbred breed showed less variability, likely due to centuries of targeted breeding that modified the gene pool.

Research Methodology

• The scientists studied blood protein polymorphism – variation in protein types – in two breeds of horses: the Thoroughbred (TB) and the Argentine Creole (AC).
• They worked with a sample size of 200 Thoroughbreds and 124 Argentine Creoles.
• Five blood proteins were analyzed: albumin (Al), esterase (Es), alpha(1)B-glycoprotein (Xk), transferrin (Tf), and hemoglobin (Hb).

Research Findings

• Two of the systems tested (Tf and Hb) were not in Hardy-Weinberg equilibrium for either breed. This condition suggests that the genes are not randomly assorting, or there may be other external influences on the population such as non-random mating or mutation.
• Among the Argentine Creole breed, the esterase was also not in equilibrium, indicating potential genetic drift or selection within this breed.
• The research revealed a higher average heterozygosity (an indicator of genetic variability) in the AC horses (0.585 +/- 0.131) than in the TB horses (0.353 +/- 0.065).

Interpretation and Implications

• The differentiation measure between the two populations (F(ST)) was 0.109, suggesting that approximately 10% of the genetic difference between breeds can be attributed to breed differences.
• The other 90% of variation was due to individual differences within breeds.
• The higher degree of genetic variability in the Argentine Creole could be due to natural selection functioning with less human interference, maintaining a greater diversity of traits.
• The Thoroughbred’s reduced variability may stem from selective breeding practices that aimed at enhancing certain desirable traits, thereby reducing the diversity at certain genetic locations.
• The findings suggest that different mechanisms might exist for maintaining polymorphism (the multiple occurrences of distinct forms, or “alleles,” of a gene) in these two different horse breeds.
• Greater heterozygosity might contribute significantly to the adaptability of a breed as it denotes greater genetic diversity.