# Differentiating Pigs from Wild Boars Based on _Nr6a1_ and _Mc1r_ Gene Polymorphisms
## 4 Discussion  
The _MC1R_ polymorphism in wild bours and domestic pigs from Poland has previously been studied by [22] and [23]. Our study expands the number of wild bours tested in central Europe and enables comparison with findings in local domestic breeds. To our knowledge, this represents the first time that the _NR6A1_ g.748C \(>\) T test has been implemented in the Polish population. The efficacy of searching for markers suitable to determine these two subspecies relies on the type of genetic marker. Choosing markers on which strong selection has been conducted (e.g., _MC1R_ and _NR6A1_) might be beneficial. _MC1R_ is one of the pivotal genes that play a significant role in determining coat/skin colour. The _MC1R_ gene polymorphism has already been proved useful in species identification of food products, e.g., authentication of Parmigiano Reggiano cheese produced only from Reggiana milk [24], or products containing meat from the Nero Siciliano pig [25]. However, basing a discriminatory analysis on only one marker in closely related taxa such as pigs and wild bours is inefficient [1; 26]. Therefore, in this study, we also used the _NR6A1_ SNP g.299084751 C \(>\) T (p.Pro192 Leu). This marker is related to higher meat efficiency in pigs, due to the longer body achieved from more thoracic vertebrae [9]. Our results are consistent with studies conducted elsewhere [1; 26]. Specifically, the homozygous genotype (TT) is prevalent in domestic breeds (Duroc, large white, and landrace pigs, Pulawska and Zlotnicka White). In contrast, European wild boar demonstrated greater frequencies of the CC genotype. According to our results, none of the four diagnostic SNPs in _MC1R_ could sufficiently differentiate the two subspecies. Nevertheless, we verified the unique _MC1R_ profile of Duroc, classified as the red (e) allele [6]. This is consistent with the Duroc coat colour pattern, which is exceptional among other breeds studied (Figure S2). A unique profile has been classified under the most distant haplotype on the haplotype network. Unlike results obtained elsewhere [6; 22; 26], not all Durocs were e/e homozyggotes in our study. Of particular interest is the wild type genotype (E\({}^{+}\)/E\({}^{+}\)) identified in one Duroc sample. STRUCTURE software analysis reflected these results and assigned the E\({}^{+}\)/E\({}^{+}\) Duroc samples to the wild boar cluster. The identification of wild type alleles in commercial pig breeds is not common and was not found in the studies conducted by [8; 26] and [22]. In Poland, Durocs have been used in breeding programmes to improve the meat efficacy of pig breeds (e.g., PL, PLW) [27]. Concerning the aim of the study, we consider that the presence of the wild allele in this breed might have in turn been transferred to other breeds, making it difficult to differentiate both subspecies. Further studies conducted on a larger number of samples should give an insight into the frequency of the E\({}^{+}\)/E\({}^{+}\) genotype in domestic breeds. A specific e allele was found in two Zlotnicka White samples. We have not found any mention in the literature of breeding schemes introducing Duroc breed into the Zlotnicka White breed. Additionally, both Zlotnicka samples with the recessive e allele were depicted as having mixed profiles, including Duroc and other domestic breeds. Admixture of the domestic pig genome with the wild boar population was identified in previous studies carried out on Polish [22; 23] and European [26] population pigs and wild bours. Our study also found two wild boar samples representing hybrids of the wild type and domestic genotype (E\({}^{+}\)/ED1,2,P2) STRUCTURE just as haplotype files clustered these two wild bours accordingly. The identification of hybrids or genome admixture isnot dependent on the marker(s) implemented. [28] studied microsatellites in domestic breeds, captive wild boars and free-living wild boars. They identified domestic pig gene introgression into the wild population due to keeping pigs in semi-enclosed farms without human supervision.