Genetic variation of European mouflon depends on admixture of introduced individuals

In the early twentieth century, European mouflon was introduced in Croatia, while all introductions in Slovenia occurred in the 1950s and 1960s. Although majority of the introductions were historically documented, occasional cases involving individuals of unknown origin have likely contributed to a mixed genetic pool in established colonies. To understand the impact of past management and the potential founder effects on contemporary mouflon populations, we performed the first genetic study of the species in these two countries. Utilising next-generation sequencing of both mitochondrial control region (mtDNA CR) and major histocompatibility complex (MHC DRB exon 2), our study scrutinises the genetic diversity and structure of these populations. Additionally, the origins and genetic variability of mouflon in Croatia and Slovenia were compared with reference samples from Czech Republic, Sardinia (Italy), and Corsica (France). The mtDNA haplotype network showed that the majority of mouflon from Slovenia are closely related to mouflon from Sardinia, and only few shared the same haplotypes with mouflon from Croatia. Some mouflon from mainland Croatia share identical or closely related haplotypes with individuals from the initially established population in this country (on the Brijuni Archipelago), while others belong to a distinctly different cluster. We found five MHC alleles previously reported for mouflon in Europe, and genetic diversity was similar in both studied countries. We observed an excess of the Ovar-DRB1*07012/*07012 genotype, and only a few individuals exhibited the advantageous genotypes for parasite infection (Ovar-DRB1*0114 allele and Ovar-DRB1*0324/*0114 genotype). Genetic data showed that the population origins are generally in agreement with the written historical records, although we found signals of release of extra individuals into certain colonies.