Department of Plant Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18 D, SE-752 36 Uppsala, Sweden.
Ecology. 2013 Jun;94(6):1236-42. doi: 10.1890/12-1840.1.
Clarifying the relationship between environmental context and the adaptive significance of floral traits is fundamental for an understanding of spatial and temporal variation in pollinator-mediated selection. We manipulated vegetation height and pollination regime of the orchid Dactylorhiza lapponica in a factorial design to test whether pollinator-mediated selection on floral traits is stronger in tall than in short vegetation, and whether this difference is larger for visual traits affecting pollinator attraction than for traits affecting pollination efficiency. In tall vegetation, pollinators mediated strong selection for taller plants (change in selection gradient for pollination, deltabeta(poll) = 0.33), more flowers (deltabeta(poll) = 0.34), and longer spurs (deltabeta(poll) = 0.42). In short vegetation, there was no significant selection on plant height, and pollinator-mediated selection on number of flowers and spur length was reduced by 52% and 25%, respectively. The results demonstrate experimentally that vegetation context can markedly influence the strength of pollinator-mediated selection on visual display traits, and indicate that this effect is weaker for traits affecting pollination efficiency. The study illustrates how crossed manipulations of environmental factors can reveal the causal links between ecological context and selection on floral traits.
阐明环境背景与花部特征适应意义之间的关系，对于理解传粉者介导选择在时空上的变化至关重要。我们采用因子设计，人为操纵兰花 Dactylorhiza lapponica 的植被高度和传粉模式，以检验花部特征是否在高植被中比在低植被中受到更强的传粉者介导选择，以及这种差异对于影响传粉者吸引力的视觉特征是否大于影响传粉效率的特征。在高植被中，传粉者介导了对更高植株（传粉选择梯度的变化，deltabeta(poll) = 0.33）、更多花朵（deltabeta(poll) = 0.34）和更长距（deltabeta(poll) = 0.42）的强烈选择。在低植被中，对植株高度没有显著的选择，而对花朵数量和距长度的传粉者介导选择则分别减少了 52%和 25%。研究结果从实验上证明了植被背景可以显著影响视觉展示特征的传粉者介导选择的强度，并表明对于影响传粉效率的特征，这种影响较弱。该研究说明了如何通过交叉操纵环境因素来揭示生态背景与花部特征选择之间的因果关系。
