Genetic analysis of hybridization between domesticated endangered pig breeds and wild boar

Black Slavonian (DBS) pig and Turopolje pig (DTP) are endangered autochthonous Croatian pig breeds that are still reared in a traditional way under semi-wild conditions in an area populated with growing wild boar populations. This raises the possibility of hybridization between domestic pigs and wild boars, a possibility often debated but rarely analyzed genetically. We analyzed potential hybridization between populations of domestic pigs (DBS, N=28; DTP, N=46) and wild boars (WBS) in eastern and western Slavonia (N=20 each) using 14 microsatellite markers and a Bayesian clustering algorithm (STRUCTURE). The STRUCTURE analysis classified all animals into corresponding WBS, DBS and DTP clusters. However, the DTP cluster contained four DTP animals with WBS membership coefficients (q) ranging from 0.25 to 0.35. These results provide genetic evidence of recent gene flow from WBS into DTP. We recommend monitoring the purity of DTP individuals to preserve the genetic integrity of this critically endangered breed. More generally, our findings provide an example of multiple hybridization events in the history of pig domestication.