How we look: European wild mouflon and feral domestic sheep hybrids.

Hybridization between wild animals and feral individuals from closely related domestic species can occur when they share the same habitat. Such events are generally regarded as a threat to the genetic integrity and survival of established wild populations. The aim of this study is to confirm a hybridization between European mouflon and feral sheep on the Adriatic island Dugi Otok, where a group of individuals phenotypically indicative of a possible introgression was photographed. Using an ovine medium-density SNP array genotypes, we provided genetic evidence of recent gene admixture between the two species. The ADMIXTURE analysis suggests that two hybrid individuals had 82.2% and 94.1% of their ancestry attributable to feral sheep, respectively, with the rest of the mouflon in origin. NEWHYBRIDS analysis estimated the combined probabilities for the putative hybrid individuals belonging to one of the hybrid classes at 87.0% and 90.1%, respectively. The main phenotypic differences in the hybrids were observed in the shape of the horns, a stronger horn circumference than in the mouflon and weaker than for the sheep, pronounced horn rings, a shorter tail, and intermediate color. We therefore recommend constant monitoring of the purity of the mouflon population to maintain its genetic integrity. In addition, all feral sheep should be removed from the wild, and released sheep raised in semi-wild conditions should be better controlled.