Abrahamczyk Stefan, Weigend Maximilian, Becker Katrin, Dannenberg Lea Sophie, Eberz Judith, Atella-Hödtke Nayara, Steudel Bastian
Nees Institute for Biodiversity of Plants University of Bonn Bonn Germany.
Health and Environmental Sciences Xi'an Jiaotong-Liverpool University Suzhou China.
Ecol Evol. 2022 Feb 17;12(2):e8621. doi: 10.1002/ece3.8621. eCollection 2022 Feb.
Many hummingbird-pollinated plant species evolved from bee-pollinated ancestors independently in many different habitats in North and South America. The mechanisms leading to these transitions are not completely understood. We conducted pollination and germination experiments and analyzed additional reproductive traits in three sister species pairs of which one species is bee- and the other hummingbird-pollinated. All hummingbird-pollinated species showed higher seed set and germination rates in cross-pollinated than in self-pollinated flowers. In the self-compatible, bee-pollinated sister species this difference did not exist. As expected, seed set and germination rate were higher after cross-pollination in the largely self-incompatible genus independently of the pollination syndrome. However, the bird-pollinated species produce only half of the amount of ovules and pollen grains per flower compared to the bee-pollinated sister species. This indicates that hummingbird pollination is much more efficient in self-incompatible populations because hummingbirds waste less pollen and provide higher outcrossing rates. Therefore, hummingbird pollination is less resource costly. Overall, we suggest that hummingbirds may increase the reproductive success compared to bees, influencing the evolution of hummingbird pollination in ecosystems with diverse bee assemblages.
许多由蜂鸟传粉的植物物种是在南北美洲的许多不同栖息地从由蜜蜂传粉的祖先独立进化而来的。导致这些转变的机制尚未完全被理解。我们进行了授粉和发芽实验，并分析了三个姊妹物种对的其他繁殖特征，其中一个物种由蜜蜂传粉，另一个由蜂鸟传粉。所有由蜂鸟传粉的物种在异花授粉时的结实率和发芽率都高于自花授粉的花朵。在自交亲和、由蜜蜂传粉的姊妹物种中，这种差异不存在。正如预期的那样，在很大程度上自交不亲和的属中，异花授粉后的结实率和发芽率更高，与授粉综合征无关。然而，与由蜜蜂传粉的姊妹物种相比，由蜂鸟传粉的物种每朵花产生的胚珠和花粉粒数量只有一半。这表明在自交不亲和的种群中，蜂鸟传粉效率更高，因为蜂鸟浪费的花粉更少，异交率更高。因此，蜂鸟传粉的资源成本更低。总体而言，我们认为与蜜蜂相比，蜂鸟可能会提高繁殖成功率，影响具有多样蜜蜂群落的生态系统中蜂鸟传粉的进化。
