Data from: Crop-to-wild gene flow and its fitness consequences for a wild fruit tree: towards a comprehensive conservation strategy of the wild apple in Europe

Crop-to-wild gene flow can reduce the fitness and genetic integrity of wild species. Malus sylvestris, the European crabapple fruit tree, in particular is threatened by the disappearance of its habitat and by gene flow from its domesticated relative, Malus domestica. With the aims of evaluating threats for M. sylvestris and of formulating recommendations for its conservation, we studied here, using microsatellite markers and growth experiments: i) hybridization rates in seeds and trees from a French forest and in seeds used for replanting crabapples in agrosystems and in forests, ii) the impact of the level of M. domestica ancestry on individual fitness tree, and iii) pollen dispersal abilities in relationship with crop-to-wild gene flow. We found substantial contemporary crop-to-wild gene flow in crabapple tree populations and superior fitness of hybrids compared to wild seeds and seedlings. Using paternity analyses, we showed that pollen dispersal could occur up to 4 km and decreased with tree density. The seed network furnishing the wild apple reintroduction agroforestry programs was found to suffer from poor genetic diversity, introgressions, and species misidentification. Overall, our findings indicate supported threats for the European wild apple steering us to provide precise recommendations for its conservation.作物向野生近缘种的基因流会降低野生物种的适合度与遗传完整性。其中，欧洲野苹果（Malus sylvestris）作为欧洲野生苹果树种，其生存正受到栖息地丧失以及与其驯化近缘种苹果（Malus domestica）基因流的双重威胁。本研究以评估欧洲野苹果所面临的威胁并制定其保护建议为目标，采用微卫星标记（microsatellite markers）与生长实验开展了三项研究：一是法国某森林中的种子与植株，以及农业系统与森林中用于野苹果补植的种子的杂交率；二是苹果（Malus domestica）祖先血统占比对单株野苹果适合度的影响；三是与作物-野生基因流相关的花粉传播能力。本研究发现野苹果种群中存在显著的当代作物-野生基因流现象，且杂交后代的适合度显著高于野生种子与实生苗。通过父本分析，我们证实花粉传播距离可达4公里，且传播效率随植株密度升高而降低。用于野苹果再引入农林业项目的种子网络存在遗传多样性低下、基因渐渗以及物种鉴定错误等问题。综上，本研究结果证实欧洲野苹果面临切实的生存威胁，可为其保护工作提供精准的针对性建议。