Genetic diversity and population structure of three Indian horse breeds.

This research article examines the genetic diversity and population structure of Marwari, Spiti, and Kathiawari Indian horse breeds through genotyping, revealing findings of high allelic diversity, gene diversity, and inbreeding.

Genotyping and Allelic Diversity

• A main method employed in the research involved the genotyping of 96 individual horses from the three breeds using 20 polymorphic microsatellite markers, which are DNA sequences that vary in the number of repetitions among individuals and are often used in genetic studies to evaluate genetic diversity and population structure.
• The researchers discovered 157 unique alleles (variants of the same gene) encompassing 20 polymorphic loci (genetic locations); this data was instrumental in assessing the allelic diversity among the horse breeds.
• The Marwari breed demonstrated the highest allelic diversity with an average of 5.7 (A) and 5.14 (Ar), followed by the Spiti (A = 4.9 and Ar = 4.74) and then the Kathiawari (A = 4.1 and Ar = 3.82). This suggests that the Marwari breed has the greatest genetic variability.

Gene Diversity and Inbreeding

• Looking at gene diversity, the Spiti breed topped the list (He = 0.67), followed by Marwari (He = 0.66) and Kathiawari (He = 0.59). Higher He values indicate greater gene diversity, meaning Spiti horses have the most diverse genetic makeup among the three breeds examined.
• Inbreeding levels within these breeds were found to be high—an undesirable characteristic as it could lead to an increase in harmful genetic conditions. In particular, the inbreeding estimates (referred to as ‘f’) were 0.18 for Marwari, 0.08 for Spiti, and 0.07 for Kathiawari, with Marwari being the most inbred breed.

Genetic Differentiation, Gene Flow and Conservation

• Additional analyses such as pair-wise Fst analysis, Analysis of Molecular Variance (AMOVA) and assignment tests showcased high genetic differentiation and low gene flow between the horse populations, indicating significant genetic distinction between them.
• Evidence of recent genetic bottlenecks were found in the Spiti and Kathiawari populations, suggesting these breeds have experienced significant reductions in population size recently that may decrease genetic diversity and adaptability.
• The findings from this study provide valuable information regarding these Indian horse breeds and can guide future breeding management strategies to enhance their preservation.