Next of kin next door – philopatry and socio-genetic population structure in wild boar

Dispersal patterns can have vital consequences for the transfer of genes in a
population, thus shaping its genetic make-up and structure. Genetic relationships
between individuals can, in turn, affect their social behaviour and the emergent
social organization of the population. Using combination of behavioural and
genetic data from the wild boar Sus scrofa population in Białowiez˙a Primeval
Forest (eastern Poland), we evaluated the socio-genetic structure of wild boar
groups, the spatial genetic structure of the population and dispersal patterns. We
found that wild boar post-weaning movements were largely spatially limited to the
vicinity of maternal range, with female boars showing a tendency to settle in the
direct neighbourhood of the kin and male boars dispersing further away from the
natal area. Consequently, such dispersal patterns were reflected in the kin-based
social organization and the spatial genetic structure of the population, which was
manifested at a spatial scale corresponding to the size of a few home ranges
(<5 km). A negative relationship between geographic distance and genetic relatedness,
which was particularly strong in female boars, indicated a presence of local
kin clusters dominated by female boars and the importance of female philopatry
in shaping the structure of wild boar population. This was confirmed by the
genetic profile and composition of social groups. This study showed the role
dispersal decisions can play in the emergence of the kin-based and matrilineal
social system of wild boars.