Genetic evidence for past hybridisation between domestic pigs and English wild boars

Abstract

While governments normally take action to eradicate or control feral populations of introduced species, management becomes problematic in the rare event of an inadvertent reintroduction of a locally extinct species to its former range. Free-living wild boars became extinct in Britain around 700 years ago, but animals have recently escaped from farms and recolonised parts of England. There has been much debate about the potential ecological and economic impacts of the presence of feral populations of wild boar in England. Predicted negative impacts include disease transmission to domestic pigs, crop damage and problems caused by the species’ rooting behaviour. Perhaps the strongest argument in favour of the wild boars in England is the restoration of a formerly native species. However, for the re-established populations to have an intrinsic value as an addition to English biodiversity, it would be preferable if the animals were genetically pure wild boars. We used four genetic marker systems to assess the genetic status of a wild boar population in the Forest of Dean, western England. We found high frequencies of alleles of domestic origin at the mitochondrial control region and a nuclear pseudo-gene. Microsatellite-based analyses also suggested that English wild boars had a mixed wild boar/domestic pig ancestry. Therefore, it is debatable whether the wild boar in the Forest of Dean can be regarded as a restored native species.