Gene flow and reproductive success in ash (Fraxinus excelsior L.) in the face of ash dieback: restoration and conservation

Abstract • Key message Ash dieback decreases individual reproductive success of ash trees leaving healthy overrepresented as seed and pollen parents for next-generation seedlings. Substantial gene flow over hundreds meters combined with superior fertility creates optimism the species’ future in European forests. Context Hymenoscyphus fraxineus is causing high mortality ( Fraxinus excelsior L.). Due to inheritable resistance pathogen, natural selection likely act favour improved forests following regeneration. Still, frequency low, effect will depend on survival, dispersal capacity under conditions. Aims We aim test whether contribute more next generation infer their potential dispersing progenies across forested landscape. Methods Using parentage modelling, we estimate mating parameters distances seeds compare realised that unhealthy ones. Results Healthy are randomly sampled seedlings forest, although pronounced female side. observe long events mean 67 m 347 m, respectively. Conclusion Variation results lowered susceptibility dieback. The large risk genetic bottlenecks inbreeding allows resistant disperse genes into neighbourhoods substantial sizes.