Del Carmen Salas-Arcos Lucía, Lara Carlos, Castillo-Guevara Citlalli, Cuautle Mariana, Ornelas Juan Francisco
Centro de Investigación en Ciencias Biológicas, Universidad Autónoma de Tlaxcala (UAT), Km 10.5 Autopista Tlaxcala-San Martín Texmelucan, San Felipe Ixtacuixtla, 90120, Tlaxcala, Mexico.
Departamento de Ciencias Químico-Biológicas, Universidad de las Américas Puebla (UDLAP), San Andrés Cholula, Puebla, Mexico.
Naturwissenschaften. 2018 Dec 17;106(1-2):1. doi: 10.1007/s00114-018-1595-4.
The pollination syndrome concept implies that flowers evolved with particular sets of characteristics, such as colors, shapes, orientations, and rewards, as a means of attracting pollinators. However, these traits may have also evolved to deter unwanted visitors. The North American genus Penstemon exhibits a great floral diversity that is mainly associated with bumblebee and hummingbird pollination. Evolutionary shifts from insect pollination to hummingbird pollination have occurred in Penstemon repeatedly, but some species maintain mixed-pollination systems and intermediate floral traits between bee- and hummingbird-pollination modes. The apparently intermediate floral traits of species with mixed-pollination systems might be potentially acting to deter bumblebee foragers. Then, bird-flower traits might be selected with increased hummingbird visitation over evolutionary time might, resulting in specialization to and the evolution of floral traits present in hummingbird-pollinated species. Here, we modified bee-pollination floral traits in Penstemon gentianoides with a mixed pollination system, to resemble hummingbird-pollination traits, and measured the effects of trait modification on bumblebee foraging behavior and plant female reproductive fitness. Our results showed that reduction in the width of the corolla tube and the absence of the corolla lip negatively affects bumblebee visitation and their efficiency as pollinators, and that the synergistic interaction of both traits enhanced the "anti-bee" effect. We conclude that acquisition of floral traits that resemble those of hummingbird-pollination enables Penstemon plant species to deter bumblebee visits.
传粉综合征概念意味着花朵进化出了特定的一系列特征，如颜色、形状、朝向和花蜜等，以此作为吸引传粉者的一种方式。然而，这些特征可能也进化出来以驱赶不速之客。北美钓钟柳属植物展现出了丰富的花部多样性，这主要与熊蜂和蜂鸟传粉有关。在钓钟柳属植物中，从昆虫传粉到蜂鸟传粉的进化转变反复发生，但一些物种维持着混合传粉系统以及介于蜜蜂传粉和蜂鸟传粉模式之间的中间花部特征。具有混合传粉系统的物种的这些明显的中间花部特征可能潜在地起到了驱赶熊蜂觅食者的作用。那么，随着时间的推移，随着蜂鸟访花次数的增加，鸟类传粉花的特征可能会被选择出来，从而导致对蜂鸟传粉物种中存在的花部特征的特化和进化。在这里，我们对具有混合传粉系统的蓝钓钟柳的蜜蜂传粉花部特征进行了修改，使其类似于蜂鸟传粉特征，并测量了特征修改对熊蜂觅食行为和植物雌性繁殖适合度的影响。我们的结果表明，花冠筒宽度的减小和花冠唇的缺失对熊蜂访花及其作为传粉者的效率产生了负面影响，并且这两个特征的协同作用增强了“抗蜂”效果。我们得出结论，获得类似于蜂鸟传粉的花部特征使钓钟柳属植物能够阻止熊蜂访花。
