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Background: Pigs were domesticated independently in Eastern and Western Eurasia early during the agricultural revolution, and have since been transported and traded across the globe. Here, we present a worldwide survey on 60K genome-wide single nucleotide polymorphism (SNP) data for 2093 pigs, including 1839 domestic pigs representing 122 local and commercial breeds, 215 wild boars, and 39 out-group suids, from Asia, Europe, America, Oceania and Africa. The aim of this study was to infer global patterns in pig domestication and diversity related to demography, migration, and selection., Results: A deep phylogeographic division reflects the dichotomy between early domestication centers. In the core Eastern and Western domestication regions, Chinese pigs show differentiation between breeds due to geographic isolation, whereas this is less pronounced in European pigs. The inferred European origin of pigs in the Americas, Africa, and Australia reflects European expansion during the sixteenth to nineteenth centuries. Human-mediated introgression, which is due, in particular, to importing Chinese pigs into the UK during the eighteenth and nineteenth centuries, played an important role in the formation of modern pig breeds. Inbreeding levels vary markedly between populations, from almost no runs of homozygosity (ROH) in a number of Asian wild boar populations, to up to 20% of the genome covered by ROH in a number of Southern European breeds. Commercial populations show moderate ROH statistics. For domesticated pigs and wild boars in Asia and Europe, we identified highly differentiated loci that include candidate genes related to muscle and body development, central nervous system, reproduction, and energy balance, which are putatively under artificial selection., Conclusions: Key events related to domestication, dispersal, and mixing of pigs from different regions are reflected in the 60K SNP data, including the globalization that has recently become full circle since Chinese pig breeders in the past decades started selecting Western breeds to improve local Chinese pigs. Furthermore, signatures of ongoing and past selection, acting at different times and on different genetic backgrounds, enhance our insight in the mechanism of domestication and selection. The global diversity statistics presented here highlight concerns for maintaining agrodiversity, but also provide a necessary framework for directing genetic conservation.

Individuals can increase inclusive fitness benefits through a complex network of social interactions directed towards kin. Preferential relationships with relatives lead to the emergence of kin structures in the social system. Cohesive social groups of related individuals and female philopatry of wild boar create conditions for cooperation through kin selection and make the species a good biological model for studying kin structures. Yet, the role of kinship in shaping the social structure of wild boar populations is still poorly understood. In the present study, we investigated spatio-temporal patterns of associations and the social network structure of the wild boar Sus scrofa population in Białowieża National Park, Poland, which offered a unique opportunity to understand wild boar social interactions away from anthropogenic factors. We used a combination of telemetry data and genetic information to examine the impact of kinship on network cohesion and the strength of social bonds. Relatedness and spatial proximity between individuals were positively related to the strength of social bond. Consequently, the social network was spatially and genetically structured with well-defined and cohesive social units. However, spatial proximity between individuals could not entirely explain the association patterns and network structure. Genuine, kin-targeted, and temporarily stable relationships of females extended beyond spatial proximity between individuals while males interactions were short-lived and not shaped by relatedness. The findings of this study confirm the matrilineal nature of wild boar social structure and show how social preferences of individuals translate into an emergent socio-genetic population structure.

The wild boar (Sus scrofa) is one of the most widely distributed mammals in Europe. Its demography was affected by various events in the past and today populations are increasing throughout Europe. We examined genetic diversity, structure and population dynamics of wild boar in Central and Eastern Europe. MtDNA control region (664 bp) was sequenced in 254 wild boar from six countries (Poland, Hungary, Belarus, Ukraine, Moldova and the European part of Russia). We detected 16 haplotypes, all known from previous studies in Europe; 14 of them belonged to European 1 (E1) clade, including 13 haplotypes from E1-C and one from E1-A lineages. Two haplotypes belonged respectively to the East Asian and the Near Eastern clade. Both haplotypes were found in Russia and most probably originated from the documented translocations of wild boar. The studied populations showed moderate haplotype (0.714±0.023) and low nucleotide diversity (0.003±0.002). SAMOVA grouped the genetic structuring of Central and Eastern European wild boar into three subpopulations, comprising of: (1) north-eastern Belarus and the European part of Russia, (2) Poland, Ukraine, Moldova and most of Belarus, and (3) Hungary. The multimodal mismatch distribution, Fu's Fs index, Bayesian skyline plot and the high occurrence of shared haplotypes among populations did not suggest strong demographic fluctuations in wild boar numbers in the Holocene and pre-Holocene times. This study showed relatively weak genetic diversity and structure in Central and Eastern European wild boar populations and underlined gaps in our knowledge on the role of southern refugia and demographic processes shaping genetic diversity of wild boar in this part of Europe.

The Major Histocompatibility Complex (MHC) is a multigene family of outstanding polymorphism. MHC molecules bind antigenic peptides in the peptide-binding region (PBR) that consists of five binding pockets (P). In this study, we compared the genetic diversity of domestic pigs to that of the modern representatives of their wild ancestors, the wild boar, in two MHC loci, the oligomorphic DQA and the polymorphic DRB1. MHC nucleotide polymorphism was compared with the actual functional polymorphism in the PBR and the binding pockets P1, P4, P6, P7, and P9. The analysis of approximately 200 wild boars collected throughout Europe and 120 domestic pigs from four breeds (three pureblood, Pietrain, Leicoma, and Landrace, and one mixed Danbred) revealed that wild boars and domestic pigs share the same levels of nucleotide and amino acid polymorphism, allelic richness, and heterozygosity. Domestication did not appear to act as a bottleneck that would narrow MHC diversity. Although the pattern of polymorphism was uniform between the two loci, the magnitude of polymorphism was different. For both loci, most of the polymorphism was located in the PBR region and the presence of positive selection was supported by a statistically significant excess of nonsynonymous substitutions over synonymous substitutions in the PBR. P4 and P6 were the most polymorphic binding pockets. Functional polymorphism, i.e., the number and the distribution of pocket variants within and among populations, was significantly narrower than genetic polymorphism, indicative of a hierarchical action of selection pressures on MHC loci.

Among the European fauna, the Sardinian hare (Lepus sp.) is peculiar in that it differs from all other hares inhabiting the continent. Here, we report on the variation of a 461 bp sequence of hypervariable domain 1 of the mitochondrial control region, examined in 42 hares collected throughout Sardinia and compared to the corresponding sequences of different Lepus taxa. Seventeen novel haplotypes were found in the Sardinian population, resulting in a haplotype diversity of 0.840 and a nucleotide diversity of 0.012. As a result of Bayesian and principal coordinates analyses, Sardinian hares were grouped with North African hares, constituting a monophyletic clade that diverges from all other Old World hares, including Cape hares from South Africa and East Asia. Hence, our data agree that populations inhabiting North Africa and Sardinia form a distinct taxon, which could possibly be included in the L. capensis superspecies. Moreover, two corresponding lineages can be found in Sardinia and Tunisia, providing evidence of a common origin of the two populations and thus supporting the hypothesis that North African hares were introduced into the island in historical times. Our data show that the two lineages differ in their geographic distribution throughout the island and that the wild Sardinian population also shows the signature of a postintroduction demographic expansion.