Domesticated honeybees facilitate interspecific hybridization between two Taraxacum congeners
2018
Peng, Youhong | Dong, Yuran | Xu, Haigen | Xi, Xinqiang | Niklas, Karl J. | Sun, Shucun
Interspecific hybridization is common in plants under natural conditions, but the ecological mechanisms underlying when and how it happens have not fully been understood. Taraxacum calanthodium and Taraxacum 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. 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. Experiments show that both T. 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. 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.
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