Silene nutans is widely spread over Europe and shows a wide morphological variation. Based on ecological and morphological traits, edaphic ecotypes were identified in Belgium, which were also genetically differentiated based on molecular markers. Further investigations, with new molecular techniques (plastid DNA and nuclear microsatellites) allowed the identification of seven genetic lineages across Europe related to allopatric divergence in separate glacial refugia during Quaternary climate oscillations and postglacial migrations. Cross experiments showed evidence of reproductive isolation between lineages, most likely due to cytonuclear incompatibilities, suggesting that S. nutans is rather a complex of several species. We will present our on-going efforts to assess the most probable evo-demographic speciation scenarios, to quantify the level of reproductive isolation between these species and the search for genetic cytonuclear incompatibilities.