Kuppler J, Wieland J, Junker R R, Ayasse M
Institute of Evolutionary Ecology and Conservation Genomics, Ulm University, Ulm, Germany.
Evolutionary Ecology of Plants, Department of Biology, Philipps-University Marburg, Marburg, Germany.
AoB Plants. 2021 Jan 6;13(1):plab001. doi: 10.1093/aobpla/plab001. eCollection 2021 Feb.
Reduced water availability can cause physiological stress in plants that affects floral development leading to changes in floral morphology and traits that mediate interactions with pollinators. As pollinators can detect small changes in trait expressions, drought-induced changes in floral traits could affect pollinator visitations. However, the linkage between changes in floral traits and pollinator visitations under drought conditions is not well explored. We, therefore, tested whether drought-induced changes in floral morphology and abundance of flowers are linked to changes in pollinator visitations. We conducted flight cage experiments with a radio frequency identification system for automated visitation recordings with bumble bees () and common charlock () as the model system. In total, we recorded interactions for 31 foraging bumble bees and 6569 flower visitations. We found that decreasing soil moisture content correlated with decreasing size of all measured morphological traits except stamen length and nectar tube width. The reductions in floral size, petal width and length, nectar tube depth and number of flowers resulted in decreasing visitation rates by bumble bees. These decreasing visitations under lower soil moisture availability might be explained by lower numbers of flowers and thus a reduced attractiveness and/or by increased difficulties experienced by bumble bees in handling smaller flowers. Whether these effects act additively or synergistically on pollinator behaviour and whether this leads to changes in pollen transfer and to different selectionp ressures require further investigation.
水分供应减少会导致植物产生生理压力，影响花的发育，进而导致花的形态和介导与传粉者相互作用的性状发生变化。由于传粉者能够察觉性状表达的细微变化，干旱引起的花性状变化可能会影响传粉者的访花行为。然而，干旱条件下花性状变化与传粉者访花行为之间的联系尚未得到充分研究。因此，我们测试了干旱引起的花形态和花数量的变化是否与传粉者访花行为的变化有关。我们使用射频识别系统进行飞行笼实验，以熊蜂（ ）和野芥菜（ ）作为模型系统，自动记录访花情况。我们总共记录了31只觅食熊蜂的相互作用和6569次花访。我们发现，土壤水分含量的降低与除雄蕊长度和蜜管宽度外所有测量形态性状的大小减小相关。花大小、花瓣宽度和长度、蜜管深度和花数量的减少导致熊蜂访花率降低。在较低土壤水分条件下访花率下降，可能是由于花数量减少，从而吸引力降低，和/或熊蜂处理较小花朵时遇到的困难增加所致。这些影响对传粉者行为是起累加作用还是协同作用，以及这是否会导致花粉传播的变化和不同的选择压力，还需要进一步研究。
