Architecture of Ancestral Genomic Components in the Sicilian Mastiff

The Sicilian Mastiff (or Mannara dog), is an indigenous Sicilian livestock guardian dog (LGD) breed with approximately 700 registered individuals. Formal recognition as a distinct breed was conferred by the Italian Kennel Club in 2023 and efforts to attain international recognition are ongoing. Previous studies have identified the Maremma and the Abruzzes sheepdog as the closest relative of the Sicilian Mastiff, highlighting a shared history and overlapping functional characteristics typical of LGDs. Thus, investigating the genetic makeup of the Sicilian Mastiff becomes essential to safeguarding and enhancing its cultural heritage and role in Sicilian pastoralism. In this study, the genetic investigation of 12 Sicilian Mastiffs revealed significant divergence from other breeds, while also confirming a close genetic relationship with the Maremma sheepdog. Therefore, local ancestry inference analyses were performed to identify genomic regions potentially influenced by the Maremma sheepdog, in comparison with other European and Mediterranean LGD breeds. Several genomic regions exhibited strong introgression with the Maremma sheepdog. Among the genes within highly introgressed (99th percentile) regions identified in at least three of these comparisons, several were associated with traits characteristic of LGD. These traits included behavioral attributes such as aggression towards strangers, morphological features such as drop ears, and physical attributes enhancing their guarding abilities. These findings support the hypothesis that centuries of selective pressures shaped the Sicilian Mastiff, highlighting its genetic and cultural value for pastoral communities. To explore the Sicilian Mastiff’s genetic evolution and adaptability, extensive sampling is being conducted to assess changes in its genetic variability and structure over the past decade. During this period, breeders have been encouraged to adopt more stringent and informed selection practices. This longitudinal approach aims to provide valuable insights into the impact of modern management practices on the genetic profile of the breed.