The Lusitano horse maternal lineage based on mitochondrial D-loop sequence variation.

The research focuses on the genetic history of the Lusitano breed of horses, using mitochondrial D-loop sequences from founder mares and finding a significant amount of haplotype clusters common with other horse breeds. This implies multiple domestication events over time in various geographic locations. However, there is a high prevalence of a specific cluster associated with Iberian and Northern African breeds, suggesting a possible center of horse domestication in the Iberian Peninsula.

Analysis of Mitochondrial D-loop Sequences

• The researchers analyzed mitochondrial D-loop sequences, a part of the DNA present in the mitochondria that serves as an excellent marker for studying evolutionary history and genetic diversity. They examined 408 base pair sequences from 145 Lusitano founder mares.
• The analysis yielded 27 different haplotypes, which are essentially unique combinations of differences (or variations) in the D-loop sequence.
• These genetic variations were not evenly distributed. The three most common sequences represented the majority (56.5%) of the Lusitano founder mares, while half of the total types (14 haplotypes) were rare and only found once in the sample size.

Haplotype Clustering and Comparison with Other Breeds

• These haplotypes formed four main clusters in the Lusitano breed.
• When compared to haplotypes of other horse breeds, the researchers found that these clusters fall in groups shared with those breeds. This finding supports the theory of multiple domestication events taking place across different areas and periods.

Indications of Iberian Peninsula Domestication

• The researchers expanded their analysis to include 55 Pura Raza Espanola and 18 Sorraia sequences. They found that half of the total samples (50.9%) fall into a specific cluster (A).
• This cluster A has been described earlier as common in the Iberian and Northern African horse breeds.
• The high frequency of this cluster, along with its phylogeographic structure (the geographical distribution of genetic traits), indicates the possibility of a center of horse domestication in the Iberian Peninsula.