Data from: Selfing can facilitate transitions between pollination syndromes

Pollinator-mediated selection on plants can favor transitions to a new pollinator depending on the relative abundances and efficiencies of pollinators present in the community. A frequently observed example is the transition from bee pollination to hummingbird pollination. We present a population genetic model that examines whether the ability to inbreed can influence evolutionary change in traits that underlie pollinator attraction. We find that a transition to a more efficient, but less abundant pollinator is favored under a broadened set of ecological conditions if plants are capable of delayed selfing rather than obligately outcrossing. Delayed selfing allows plants carrying an allele that attracts the novel pollinator to reproduce even when this pollinator is rare, providing reproductive assurance. In addition, delayed selfing weakens the effects of Haldane's sieve by increasing the fixation probability for recessive alleles that confer adaptation to the new pollinator.
Our model provides novel insight into the paradoxical abundance of recessive mutations in adaptation to hummingbird attraction. It further predicts that transitions to efficient but less abundant pollinators (such as hummingbirds in certain communities) should disproportionately occur in self-compatible lineages. Currently available mating system datasets are consistent with this prediction and we suggest future areas of research that will enable a rigorous test of this theory.

传粉者介导的选择（Pollinator-mediated selection）作用于植物时，其是否会推动植物转向新型传粉者，取决于群落中现存传粉者的相对丰度与传粉效率。其中最常被观测到的转型案例，便是从蜂类传粉转向蜂鸟传粉。本研究构建了种群遗传模型（population genetic model），用以探究近交能力是否会影响传粉吸引相关性状的演化改变。研究结果显示：若植物具备延迟自交（delayed selfing）能力而非专性异交（obligately outcrossing），那么在更宽泛的生态条件下，植物更倾向于转向效率更高但丰度更低的传粉者。延迟自交可使携带吸引新型传粉者等位基因的植物，即便该传粉者较为稀少时仍能完成繁殖，从而提供繁殖保障。此外，延迟自交能够削弱霍尔丹筛（Haldane's sieve）的效应，提升可适配新型传粉者的隐性等位基因（recessive alleles）的固定概率。
本模型为‘适配蜂鸟传粉的适应性演化中隐性突变丰度反常偏高这一悖论’提供了全新视角。研究进一步预测：向高效但低丰度传粉者（如部分群落中的蜂鸟）的转型，应不成比例地发生在自交亲和谱系中。目前现有的交配系统（mating system）数据集与该预测相符，我们还提出了可用于严格检验该理论的未来研究方向。