Data from: Domesticated honeybees facilitate interspecific hybridization between two Taraxacum congeners

1. Interspecific hybridization is common in plants under natural conditions, but the ecological mechanisms underlying when and how it happens have not fully been understood.
2. Taraxacum calanthodium and T. lugubre are two herbaceous annals co-occurring in alpine meadows of the eastern Tibetan Plateau that share the same pollinators including domestic honeybees during their overlapping flowering times. Because honeybees tend to visit flowers less discriminatively when bee densities are high, we hypothesized that intense apiculture would facilitate hybridization between these two congeneric species.
3. We tested this hypothesis by examining the frequencies of the two parent species occurrence and the hybrid (based on morphological and genetic differences) along three transects radiating from well-established apiaries.
4. Experiments show that both Taraxacum calanthodium and T. lugubre produce seeds sexually and asexually, and that they can hybridize via pollen transfer. Bee visitation rates and the frequency of the hybrid were significantly higher in the sites nearest to apiaries compared to distant site along each of the three transects. The hybrids were consistently genetically intermediate between the two species, as indicated by Simple Sequence Repeat- based analyses.
5. Synthesis. These data indicate that domestic honeybees foster interspecific hybridization between the two Taraxacum species and that anthropogenic effects on pollen vectors can significantly influence species hybridization in nature. We suggest that more effort should be made to quantify the effects of environmental change on pollinators and their effects on species evolution.

1. 自然条件下植物的种间杂交（interspecific hybridization）较为普遍，但支撑其发生时机与路径的生态学机制尚未完全明晰。
2. *Taraxacum calanthodium*与*T. lugubre*是两种一年生草本植物，二者同域分布于青藏高原东部高寒草甸，在花期重叠时段共享包括家养蜜蜂在内的传粉昆虫。鉴于蜜蜂在种群密度较高时访花的选择性会下降，我们提出假说：高强度养蜂活动会促进这两个同属物种之间的种间杂交。
3. 我们沿三条从成熟养蜂场向外辐射的样带，基于形态学与遗传学差异对两个亲本物种及杂交个体的出现频率进行调查，以此检验该假说。
4. 实验表明，*Taraxacum calanthodium*与*T. lugubre*均可通过有性生殖与无性生殖产生种子，且二者可通过花粉传递发生杂交。在三条样带中，距养蜂场最近的样地的蜜蜂访花频率与杂交个体出现频率均显著高于较远样地。基于简单序列重复（Simple Sequence Repeat）标记的分析结果显示，所有杂交个体的遗传背景均处于两个亲本物种之间。
5. 综合分析表明：本研究数据证实家养蜜蜂可促进两种蒲公英之间的种间杂交，且人类活动对传粉媒介的影响可显著改变自然界中物种杂交的发生情况。我们建议未来应开展更多研究，以量化环境变化对传粉昆虫的影响，及其对物种演化的作用。