Saving feral horse populations: does it really matter? A case study of wild horses from Doñana National Park in southern Spain.

This study investigates the genetic characteristics of a feral horse breed, the Retuertas, from the Doñana National Park in Spain. The research aims to understand this population’s significance and genetic uniqueness in comparison with other European and North African horse breeds.

Research Subject and Methodology

The researchers focused on the Retuertas horses, a feral breed inhabiting the Guadalquivir marshes and part of a conservation program since the 1980s. Their genetic data was analyzed and compared with 10 distinct European and North African breeds. Microsatellites, which are repeating DNA sequences, were used to distinguish polymorphisms or genetic variations.

• The methodology included cataloging DNA polymorphisms from 22 different microsatellites.
• Genetic analyses were carried out, and comparisons were made between the Retuertas population and the chosen European and North African breeds.

Findings

The results revealed that the Retuertas horses have a unique genetic makeup.

• Pairwise comparisons between Retuertas and other breeds showed highly significant fixation indexes – indicating notable genetic differentiation.
• Through a neighbor-joining breed phenogram (a branching diagram representing genetic relationships), two major clusters or clades were identified for European and North African breeds. Intriguingly, the Retuertas didn’t fall into either of these clades, underscoring their genetic distinctiveness.
• In fact, the Retuertas were placed at the base of the genetic trees, which were rooted with donkey samples, suggesting a distinctive genetic lineage.

Implications and Future Directions

The study also points out potential future directions for conservation programs.

• Assignment tests and individual Q-matrices derived from the structure program clearly distinguished Retuertas from other breeds, further confirming their uniqueness.
• The study found that certain local semi-feral horses called Marismeño, which currently inhabit the Guadalquivir marshes, have some microsatellite genotypes that are grouped within the Retuertas cluster. This indicates potential genetic overlap between these populations.
• The overlap raises the possibility of integrating Marismeño horses into future conservation strategies for the Retuertas. This could be instrumental in maintaining or boosting the population’s genetic diversity.