Co-flowering plant species may interact via pollinators leading to heterospecific pollen transfer with consequences for plant reproduction. What determines the severity of heterospecific pollen effect on conspecific pollen performance is unclear, but it may depend on the phylogenetic relatedness of the interactors (pollen donors and recipient). The heterospecific pollen effect might also depend on the extent to which plants are exposed to heterospecific pollen over ecological or evolutionary timescales. For instance, generalist-pollinated plant species might tolerate heterospecific pollen more than specialists. Here, we tested whether heterospecific pollen effects are stronger between closely related species than phylogenetically distant ones in a tropical highland community. Then, based on these results, we determined whether responses to heterospecific pollen were stronger in generalized vs. specialized plant species. We applied heterospecific pollen from close (congeneric) or distant (different families) donors alone or with conspecific pollen on stigmas of three recipient species (one generalist, Sisyrinchium wettsteinii; and two specialists, Fuchsia campos-portoi and Fuchsia regia) and scored pollen tube performance in styles. In all species, pollen from closely related donors grew pollen tubes to the base of the style indicating a high potential to interfere with seed set. Conversely, distantly related heterospecific pollen had no effect on either specialist Fuchsia species, whereas enhanced performance of conspecific pollen was observed in generalist S. wettsteinii. The strong effect of phylogenetic relatedness of donor and recipient might have obscured the role of pollination specialization, at least for the three species examined here. Therefore, phylogenetic relatedness mediated the effect of heterospecific pollen on post-pollination success, with possible consequences for reproductive trait evolution and community assembly for further studies to explore.

中文翻译：

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异种花粉沉积对花粉管生长的影响取决于供体和受体之间的系统发育相关性。

共同开花的植物物种可能通过授粉媒介相互作用，导致异种花粉转移，从而影响植物繁殖。决定异种花粉对同种花粉性能影响的严重性的因素尚不清楚，但这可能取决于相互作用者（花粉供体和受者）的系统发育相关性。异种花粉效应还可能取决于植物在生态或进化时间尺度上暴露于异种花粉的程度。例如，通才授粉的植物物种对异花粉的耐受性可能比专家更大。在这里，我们测试了在热带高地社区中，密切相关的物种之间的异种花粉效应是否比系统发育上较远的物种更强。然后，根据这些结果，我们确定了广义植物物种与特殊植物物种对异种花粉的反应是否较强。我们仅将近亲（同类）或远亲（不同家庭）供体的异种花粉或同种花粉应用于三种接受物种的柱头上（一个通才，硅锡霉; 和两位专家Fuchsia campos-portoi和Fuchsia regia），并对花粉管的表现进行了评分。在所有物种中，密切相关的供体的花粉使花粉管生长到花柱的基部，表明其有可能干扰结实。相反，远距离相关的异种花粉对这两种紫红色专业种均没有影响，而在通才S中观察到同种花粉的性能增强。维特施泰因。捐助者和接受者之间的亲缘关系的强大影响可能已经掩盖了授粉专业化的作用，至少对于这里研究的三个物种而言。因此，系统发育相关性介导了异种花粉对授粉后成功的影响，可能对生殖性状的进化和群落的组装产生影响，有待进一步研究。