Beach evening-primrose (Oenothera drummondii subsp. drummondii) is a perennial herb native to the coastal dunes of the Gulf of Mexico and southeastern USA. During the last century, the species was unintentionally introduced into coastal dune systems around the world. The purpose of this study was to explore the means of dispersal of this invasive in the newly established populations on the coastal dunes of Spain and to determine if they contribute significantly to the invasion process. After reconstructing the history of its spread in Spain from available records, we tested whether dispersion by marine currents can be a mechanism of colonization at regional scale, and whether the presence of native vertebrate participate in the expansion process at local scale. Through laboratory experiments, we demonstrated that the seeds of O. drummondii can be dispersed by seawater, since 0.63% present both buoyancy in seawater and subsequent germination after being washed with fresh water. This capacity for dispersal by marine currents could explain both the expansion of the species along the southwestern coast of Spain and the maintenance of its populations following disturbances such as storms. We also demonstrated that Iberian Hares and European Rabbits can disperse the seeds by endozoochory; seeds recovered from faecal pellets of these species were capable of germination (73 and 63%, respectively). Oenothera drummondii has become an invader only in coastal dunes where these dispersers are present, and with no control actions to regulate their populations. In conclusion, O. drummondii is an alien species with varying dispersal methods, polychory. This helps maintain already established populations and disperses seeds at a regional level, depending on the incidence of storms and the presence or absence of rabbits and hares for efficient local seed dispersion. Thus, management actions that restrict marine and animal dispersal likely have the benefit of limiting the invasive potential of O. drummondii.

海滩月见草（月见草drummondii亚种drummondii）是多年生草本植物，原产于墨西哥湾和美国东南部的沿海沙丘。在上个世纪，该物种无意间被引入世界各地的沿海沙丘系统。这项研究的目的是探索在西班牙沿海沙丘上新建立的种群中传播这种侵入物的方法，并确定它们是否对入侵过程做出了重大贡献。从现有记录中重建了其在西班牙传播的历史之后，我们测试了海流的扩散是否可以是区域规模上的殖民化机制，以及本地脊椎动物的存在是否参与了当地范围的扩张过程。通过实验室实验，我们证明了O. drummondii的种子可以被海水分散，因为0.63％的海水既有浮力又有淡水洗后发芽。这种由海流传播的能力既可以解释该物种在西班牙西南沿海的扩张，又可以解释由于风暴等干扰而维持的种群。我们还证明了伊比利亚野兔和欧洲兔可以通过内吞将种子扩散。从这些种类的粪便颗粒中回收的种子能够发芽（分别为73％和63％）。月见草月见草仅在存在这些分散剂的沿海沙丘上入侵，并且没有控制其种群的控制措施。最后，O。drummondii是一种外来物种，具有不同的传播方法，即多重选择。这有助于维持已经建立的种群并在区域一级散布种子，具体取决于风暴的发生率以及是否存在兔子和野兔以实现有效的本地种子散布。因此，限制海洋和动物扩散的管理措施可能具有限制O. drummondii入侵潜力的好处。