The importance of flower-pollinator interactions for reproductive isolation and speciation processes in the genus Salvia: an experimental approach

鼠尾草属（鼠尾草）的特点是众所周知的“雄蕊杠杆机制”。生物力学方法和功能形态的定量分析被用来测试雄蕊杠杆的功能和它们的重要性，同域鼠尾草物种或物种形成和辐射过程中的属，分别生殖隔离。(1)在第一组实验中，我们测试了释放雄蕊杠杆所需的力和能量是否与传粉者的觅食行为有关。为此，将昆虫训练成“人造花”，并确定昆虫到达食物源所施加的力。然后将这些力与用高灵敏力测试仪测量的鼠尾草雄蕊杠杆运动和花变形所需的力进行比较。我们的研究结果表明，雄蕊杠杆是为了便于触发而进化的，释放雄蕊杠杆所需的力量与来访的昆虫无关。(2)在第二组实验中，假设进行测试，雄蕊杠杆机制代表了一个关键的功能，在稳定同域鼠尾草物种通过准确的和物种特异性的转移花粉的传粉者的预定义区域。我们的实验研究，如果不同种类的传粉者的花粉沉积的过程是足够准确的，以防止或尽量减少花粉的转移对柱头上的其他同域鼠尾草属物种。

The genus Salvia (sage) is characterised by the well-known `staminal lever mechanism'. Biomechanical methods and quantitative analyses of the functional morphology are used to test the functioning of the staminal levers and their importance for reproductive isolation among sympatric Salvia species or speciation and radiation processes in the genus, respectively. (1) In the first set of experiments, we tested if the forces and energies required to release the staminal levers are relevant for the foraging behaviour of the pollinators. For this purpose, the insects were trained to an 'artificial flower', and the forces which are exerted by the insects to get to the food source were determined. These forces were then compared to the forces necessary for the movement of the staminal levers and for the deformation of flowers in Salvia, measured with a highsensitive force test gauge. Our findings show that the staminal levers are evolved for an ease of triggering, and that the forces necessary to release the stamin al levers are irrelevant for the visiting insects. (2) In a second set of experiments, the hypothesis is tested that the staminal lever mechanism represents a key function in stabilising sympatric Salvia species via accurate and species-specific transfer of pollen on pre-defined regions of the pollinators. We study experimentally if the process of pollen deposition on different species of pollinators is accurate enough to prevent or minimise the transfer of pollen on the stigma of other sympatric Salvia species.