Projecting introgression from domestic cats into European wildcats in the Swiss Jura.

Hybridization between wild and domesticated organisms is a worldwide conservation issue. In the Jura Mountains, threatened European wildcats (Felis silvestris) have been demographically spreading for approximately the last 50 years, but this recovery is coupled with hybridization with domestic cats (Felis catus). Here, we project the pattern of future introgression using different spatially explicit scenarios to model the interactions between the two species, including competition and different population sizes. We project the fast introgression of domestic cat genes into the wildcat population under all scenarios if hybridization is not severely restricted. If the current hybridization rate and population sizes remain unchanged, we expect the loss of genetic distinctiveness between wild and domestic cats at neutral nuclear, mitochondrial and Y chromosome markers in one hundred years. However, scenarios involving a competitive advantage for wildcats and a future increase in the wildcat population size project a slower increase in introgression. We recommend that future studies assess the fitness of these hybrids and better characterize their ecological niche and their ecological interactions with parental species to elucidate effective conservation measures.