Analysis of genetic diversity and the determination of relationships among western Mediterranean horse breeds using microsatellite markers.

The research aims to analyze the distribution of genetic diversity and relationships among different breeds of western Mediterranean horses using a specific genetic identifier, called microsatellite markers. It also highlights the application of genetic markers and pedigree information in understanding population dynamics and determining conservation priorities.

Study Approach

• The researchers used microsatellite markers, a type of DNA sequence that often varies in length among different individuals of a species, to analyze the genetic diversity and relationships among different horse breeds in the Mediterranean region.
• The sample included seven breeds from Spain, three from Italy, and a Spanish Thoroughbred as an outgroup—an external comparator to those being closely examined. This sample consisted of 682 horses, with an average of 62 animals per breed, and a range between 20 and 122.

Findings

• An examination of the microsatellite markers identified 128 distinct alleles (different forms of a gene), or an average of 10.7 alleles per locus (specific location of a gene on a chromosome).
• Within each breed, the genetic diversity was high (greater than 0.70), with each breed contributing approximately 8% to the total genetic variability observed.
• The mean molecular coancestry (a measure of the genetic similarity between individuals) of the entire population was found to be 0.205, with the ‘Losino’ breed contributing the most.

Ranking and Clustering Analysis

• In addition to standard genetic and Reynolds’ genetic distances (different measures of genetic variation), pairwise kinship distance (a measure of the genetic relationship between pairs of individuals) and molecular coancestry were calculated.
• Interestingly, similar ranking of breeds was observed using all these methods.
• Clustering analysis (a statistical method used to group similar individuals or breeds together) provided an accurate representation of current genetic relationships among the breeds.

Importance of Coancestry Analysis

• Coancestry analysis helps in understanding the distribution of genetic diversity within and between breeds and offers a valuable tool for analyzing molecular markers alongside pedigree information.
• An integrated analysis involving genetic markers and pedigree information allows better understanding of population dynamics in native horse populations of the western Mediterranean. This can aid in determining conservation priorities for these breeds.