Data from: The effect of trap colour and trap-flower distance on prey and pollinator capture in carnivorous Drosera species

1. The functional features of carnivorous plants’ traps have been mostly interpreted as adaptations to capture prey. Carnivorous plants that feed on insects, however, run the risk that increasing trapping effectiveness might in turn reduce reproductive success through capture of pollinators. Such a pollinator–prey conflict might play an important role in the evolution of trap features. In carnivorous plants with sticky leaves (e.g. Drosera, Pinguicula), both spatial distance between traps and flowers and their visual signals (e.g. colour, display size) likely play a role in attracting prey but it has also been suggested that they affect the risk of potential pollinators landing on a trap. It has been reported, for example, that red pigmentation in carnivorous plants may lure insect prey to traps. This idea remains controversial, however, because colour vision of most insects does not extend very far into the red part of the spectrum. 2. We tested an alternative hypothesis, namely that red pigmentation of the trapping leaves may reduce the risk of a pollinator–prey conflict. Experiments were conducted in a natural habitat of Drosera arcturi and D. spatulata in the Southern Alps of New Zealand. Using sticky model traps similar in shape to Drosera leaf traps and flowers, we investigated the effect of colour (green vs. red vs. white) and flower-trap distance (flower stalk length and leaf arrangement, that is upright as in D. arcturi vs. flat ground rosette as in D. spatulata) on composition and abundance of insects landing and being trapped. 3. Flower-trap distance had no significant effect on the risk of pollinators being trapped but model flowers higher above the ground received more pollinator landings. Across all model traps, the number of trapped potential pollinators was significantly lower in traps with red leaves compared to green ones. 4. The results suggest that the typical red pigmentation of the trapping leaves in Drosera may be a way to protect pollinators from being attracted and captured. However, our data also suggest that pollinator protection via red traps may come with a trade-off since total prey capture was also significantly reduced.1. 食虫植物（carnivorous plants）捕虫器的功能特征，长期以来大多被视作针对猎物捕获的适应性演化特征。然而，以昆虫为食的食虫植物面临一项风险：捕虫效率的提升，可能会因误捕传粉者（pollinators）而降低繁殖成功率。这类传粉者-猎物冲突（pollinator–prey conflict），或许在捕虫器特征的演化进程中扮演着关键角色。对于具有粘性叶片的食虫植物（如茅膏菜属（Drosera）、捕虫堇属（Pinguicula））而言，捕虫器与花朵间的空间距离，以及二者的视觉信号（如色彩、展示尺寸），既可能在吸引猎物过程中发挥作用，也有研究指出这些因素会影响潜在传粉者降落在捕虫器上的风险。例如，已有研究报道食虫植物的红色色素沉着（pigmentation）可将昆虫猎物诱至捕虫器处，但该观点尚存争议，因为多数昆虫的色觉无法延伸至光谱的红光波段。 2. 本研究检验了一项备选假说：捕虫叶片的红色色素沉着，可降低传粉者-猎物冲突的发生风险。实验在新西兰南阿尔卑斯山的天然栖息地开展，研究对象为北极茅膏菜（Drosera arcturi）与匙叶茅膏菜（Drosera spatulata）。我们采用形态与茅膏菜属叶片捕虫器相似的粘性模型捕虫器，并搭配花朵模型，探究了色彩（绿色、红色与白色）以及花-捕虫器间距（由花茎长度和叶片排列决定，即北极茅膏菜的直立型结构，与匙叶茅膏菜的贴地莲座型结构）对降落并被捕获的昆虫的类群组成与丰度的影响。 3. 花-捕虫器间距对传粉者被捕食的风险无显著影响，但离地高度更高的模型花朵获得了更多传粉者的降落次数。在所有模型捕虫器中，搭载红色叶片的捕虫器所捕获的潜在传粉者数量，显著低于绿色叶片的捕虫器。 4. 研究结果表明，茅膏菜属植物捕虫叶片典型的红色色素沉着，或许是一种保护传粉者免受吸引与捕获的策略。但本研究数据同时显示，借助红色捕虫器实现的传粉者保护可能存在权衡效应：其总猎物捕获量也出现了显著下降。