Data from: Introduced Scotch broom (Cytisus scoparius) invades the genome of native populations in vulnerable heathland habitats

Cytisus scoparius is a global invasive species that affects local flora and fauna at the intercontinental level. Its natural distribution spans across Europe, but seeds have also been moved among countries, mixing plants of native and non-native genetic origins. Hybridization between the introduced and native genepool is likely to threaten both the native genepool and the local flora. In this study, we address the potential threat of invasive C. scoparius to local gene pools in vulnerable heathlands. We used nuclear single nucleotide polymorphic (SNP) and simple sequence repeat (SSR) markers together with plastid SSR and indel markers to investigate the level and direction of gene flow between invasive and native heathland C. scoparius. Analyses of population structures confirmed the presence of two gene pools; one native and the other invasive. The nuclear genome of the native types was highly introgressed with the invasive genome, and we observed advanced-generation hybrids, suggesting that hybridization has been occurring for several generations. There is asymmetrical gene flow from the invasive to the native gene pool, which can be attributed to higher fecundity in the invasive individuals, measured by the number of flowers and seed pods. Strong spatial genetic structure in plastid markers and weaker structure in nuclear markers suggest that seeds spread over relatively short distances and that gene flow over longer distances is mainly facilitated by pollen dispersal. We further show that the growth habits of heathland plants become more vigorous with increased introgression from the invaders. Implications of the findings are discussed in relation to future management of invading C. scoparius.

金雀花（Cytisus scoparius）是一种全球性入侵物种，可在洲际尺度上对本地动植物区系造成影响。其天然分布范围覆盖欧洲，但种子可在各国间传播，导致本土与外来遗传起源的植株发生混合。引入种群与本土基因库间的杂交极有可能对本土基因库及本地植物区系构成威胁。本研究聚焦入侵性金雀花对脆弱石楠灌丛本土基因库的潜在威胁展开探讨，采用核单核苷酸多态性（single nucleotide polymorphism, SNP）与简单序列重复（simple sequence repeat, SSR）标记，结合质体SSR及插入缺失（indel）标记，对入侵与本土石楠灌丛中金雀花种群间的基因流水平与方向进行分析。种群结构分析证实存在两类基因库：一类为本土基因库，另一类为入侵基因库。本土类型的核基因组已发生显著的入侵基因组渐渗，且观测到多代杂交后代，表明杂交事件已持续发生多代。研究发现存在从入侵基因库向本土基因库的不对称基因流，这一现象可归因于入侵个体更高的繁殖力——以花朵数量与荚果数量作为衡量指标。质体标记呈现较强的空间遗传结构，而核标记的空间结构相对较弱，这表明种子传播距离相对较短，长距离基因流主要依靠花粉传播介导。本研究还进一步显示，随着来自入侵种群的渐渗程度升高，石楠灌丛植物的生长势愈发旺盛。最后，我们结合金雀花入侵的未来防控管理需求，对本研究结果的应用启示进行了讨论。