Genetic structure and connectivity analysis in a large domestic livestock meta-population: The case of the Pura Raza Español horses.

The research paper explores the genetic structure and connectivity in the Pura Raza Español horse population, a breed native to Spain but globally distributed. The genetic analysis covers 215,500 horses in 27 countries, and identifies key factors influencing genetic diversity within and between populations.

Methodology

• Researchers studied the genetic structure of the Pura Raza Español (PRE) horse meta-population (MP), which includes 215,500 animals across 27 countries with at least 80 active animals each.
• Genetic analysis was done using parameters such as inbreeding (F), coancestry (the probability that two gene copies selected randomly from the population would be identical by descent), the contribution of founders, the effective number of founders/ancestors (fe/fa), and the gene flow between countries.

Results

• The study found that the inbreeding coefficient decreased in the last two decades (1990-2013), indicating a targeted management strategy against inbreeding.
• Most of the contribution to genetic variability across countries came from females (73.6%). However, there was an unbalanced contribution from founders, suggesting a high loss of genetic diversity over generations (as low as 32/19 for the whole MP).
• Despite variable contributions, each country made similar proportionate contributions to global diversity.
• The highest within-country coancestry value was seen in Cuba, the only country with highly inbred individuals (over 12%). The lowest coancestry value corresponded to Spain.
• Nine countries presented descendants in a single population, implying a common origin and/or extensive exchange of genetic material between populations. Spain and the U.S. showed the highest gene flow rates, indicating significant exchange and mixing of genes.

Implications

• The results highlight potential declines in genetic variability and increases in inbreeding levels, especially in smaller countries like Cuba.
• They also emphasize the need for a coordinated management strategy, particularly regarding the exchange of genetic material. This might boost the effective population size and maintain genetic diversity levels in the PRE horse population.