The interspecific variation in the defensive flower closure of <i>Drosera</i> (Droseraceae) is related to the herbivory pressure

Rapid plant movements in response to mechanical stimulation have long captivated mainstream interest. The flowers of <i>Drosera</i> species, notably studied for their defensive closure upon touch, protect their ovules from the specialist herbivore <i>Buckleria paludum</i> caterpillar. Although several species within <i>Drosera</i> exhibit variation in the speed of flower closure, the evolutionary and ecological contexts of these differences remain unclear. We hypothesized that the interspecific variation in flower closure speed has evolved in response to differing levels of herbivory pressure. Using <i>Drosera rotundifolia</i> and <i>D. tokaiensis</i>, we investigated the relationships between flower closure speed, effectiveness in ovule defense, herbivory pressure in nature, and the potential cost of flower closure. Our results indicate that <i>D. tokaiensis</i>, which exhibits faster flower closure than<i> D. rotundifolia</i>, more effectively reduces ovule damage due to <i>B. paludum</i> feeding attempts. Field surveys revealed that <i>D. tokaiensis</i> experiences higher herbivory pressure, likely due to its preference for drier microhabitats, which may influence the evolution of its rapid closure response. These findings enhance our understanding of the ecological and evolutionary factors driving the diversification of rapid plant movements and contribute to the emerging field of plant behavioral ecology.植物响应机械刺激的快速运动长期以来一直备受学界关注。茅膏菜属（Drosera）植物的花因受触碰时会发生防御性闭合而被广泛研究，其功能是保护胚珠免受专食性植食昆虫湿地盾卷蛾（Buckleria paludum）幼虫的取食危害。尽管茅膏菜属内多个物种的花闭合速度存在差异，但这些差异的演化与生态背景仍未明确。我们提出假说：花闭合速度的种间差异是对不同植食压力水平的适应性演化结果。本研究以圆叶茅膏菜（Drosera rotundifolia）与东海茅膏菜（D. tokaiensis）为实验材料，探究了花闭合速度、胚珠防御有效性、野外植食压力与花闭合潜在成本之间的关联。研究结果表明，相较于圆叶茅膏菜，东海茅膏菜的花闭合速度更快，能更有效地降低湿地盾卷蛾取食尝试导致的胚珠损伤。野外调查显示，东海茅膏菜面临的植食压力更高，这可能与其偏好较为干燥的微生境有关，而该生境偏好或推动了其快速闭合响应的演化。本研究结果增进了我们对驱动植物快速运动多样化的生态与演化因素的认知，同时为新兴的植物行为生态学领域贡献了新的研究视角。