Genetics as a useful tool for understanding relatedness, movements and social behaviour in wild boar

Wild boar (Sus scrofa) is a globally widely distributed species that has recently increased in population size and distribution causing more socio-economic and ecological concern than any other ungulate species. Therefore, a comprehensive understanding of the species needs is urgently needed. The wild boar has long been considered a polygynous species with strong social bonds in female-based groups. However, recent molecular studies have proved that the species is actually polygamous and the composition of social groups can vary depending on ecological and predation/hunting pressures. By combining the harvest coordinates with the genotype of each individual, we can provide additional insights into the mating and social behaviour of the species under different environmental and hunting conditions. Here we present a fine scale spatial distribution of allelic diversity and relatedness of wild boar in a 2 600 ha large typical hunting ground of central Slovenia. We genotyped 58 individuals (of both sexes and all age classes) harvested from 2017 to 2020 at 13 neutral microsatellite loci. The relatedness data was combined with exact harvest location (coordinates) to provide insight into behavioural features (e.g. seasonal dispersions and social grouping). Analysis of high-probability relatedness (>0.90) revealed one potential father, seven potential mothers and their 17 offspring (either piglets, yearlings or younger adults), and additional 19 close, but non-parental relations (i.e., full-siblings and half-siblings of both sexes and all age classes). We found many genetic relations and high degree of relatedness among the studied individuals, indicating existence of only few main maternal groups and high matrilineal effect with high side-fidelity of females and prevalence of only short dispersal of piglets in this rather small study area. Moreover, we detected a frequent multiple paternity in the studied population as we found six litters (with majority of siblings within a particular litter shot together) with different fathers.