Due to drastic changes in pollinators between native and invaded habitats, we might expect that pollinator-mediated selection on floral traits of alien plants differ from that in their native ranges. Here, through geometric morphometric tools and phenotypic selection analyses, we examined whether adaptation in flower shape and length occurred in Nicotiana glauca as a response to pollinator selection in contrasting pollination environments. We assessed populations of this plant species in the native range (South America), where plants depend on hummingbird pollination, and in two invaded areas, one where sunbirds act as pollinators (South Africa), and another where nectar feeding birds are absent and reproduction is entirely by autonomous self-pollination (Mallorca, Spain). Corolla length and shape varied significantly among pollination environments. Non-native sites were less variable and their range of variation fell within the native range of variation. Flower length in native populations and in a South African population matched the bill length of their respective pollinators. In contrast with the straight floral tubes in the native range, both non-native areas had significantly curved tubes. Curvature may improve the fit with the curved bills of sunbirds in South Africa (versus straight beaks of hummingbirds) and may enhance self-pollination in Mallorca, but this similarity between invaded areas may equally be due to drift and a shared colonization route. We found spatial variation in selection acting on corolla length but not on corolla shape. Overall, selection patterns were not consistent with floral trait variation. Although some results are consistent with both drift and selection, our study suggests that population divergence in flower shape and length is more likely the result of long-term diversifying pollinator-driven selection, which is difficult to detect by studying a single selection event.

中文翻译：

---

Nicotiana glauca 本地和非本地种群之间花朵形状和长度的变化是否是传粉媒介介导的选择的产物？

由于本地和入侵栖息地之间传粉媒介的剧烈变化，我们可能期望传粉媒介介导的外来植物花卉性状选择与其本土范围内的不同。在这里，通过几何形态测量工具和表型选择分析，我们检查了烟草花形状和长度的适应性是否发生在对比授粉环境中作为对授粉媒介选择的反应。我们评估了这种植物物种在原生范围（南美洲）和两个入侵地区的种群数量，该地区的植物依赖蜂鸟授粉，一个是太阳鸟作为传粉者（南非），另一个是不存在以花蜜为食的鸟类并繁殖的地区完全通过自主自花授粉（西班牙马略卡岛）。花冠长度和形状在授粉环境中差异很大。非本地站点的可变性较小，其变异范围落在本地变异范围内。本地种群和南非种群的花长度与其各自传粉者的喙长度相匹配。与原生范围内的直花管相比，两个非原生区域都有明显弯曲的管。曲率可能会改善与南非太阳鸟弯曲喙的配合（相对于蜂鸟的直喙），并可能增强马略卡岛的自花授粉，但入侵区域之间的这种相似性可能同样是由于漂移和共享的殖民路线。我们发现选择的空间变化作用于花冠长度而不是花冠形状。全面的，选择模式与花卉性状变异不一致。尽管一些结果与漂移和选择一致，但我们的研究表明，花形和长度的种群差异更有可能是传粉媒介驱动选择的长期多样化的结果，这很难通过研究单个选择事件来检测。