Despite sometimes strong codependencies of insect herbivores and plants, the responses of individual taxa to accelerating climate change are typically studied in isolation. For this reason, biotic interactions that potentially limit species in tracking their preferred climatic niches are ignored. Here, we chose butterflies as a prominent representative of herbivorous insects to investigate the impacts of temperature changes and their larval host plant distributions along a 1.4-km elevational gradient in the German Alps. Following a sampling protocol of 2009, we revisited 33 grassland plots in 2019 over an entire growing season. We quantified changes in butterfly abundance and richness by repeated transect walks on each plot and disentangled the direct and indirect effects of locally assessed temperature, site management, and larval and adult food resource availability on these patterns. Additionally, we determined elevational range shifts of butterflies and host plants at both the community and species level. Comparing the two sampled years (2009 and 2019), we found a severe decline in butterfly abundance and a clear upward shift of butterflies along the elevational gradient. We detected shifts in the peak of species richness, community composition, and at the species level, whereby mountainous species shifted particularly strongly. In contrast, host plants showed barely any change, neither in connection with species richness nor individual species shifts. Further, temperature and host plant richness were the main drivers of butterfly richness, with change in temperature best explaining the change in richness over time. We concluded that host plants were not yet hindering butterfly species and communities from shifting upwards. However, the mismatch between butterfly and host plant shifts might become a problem for this very close plant–herbivore relationship, especially toward higher elevations, if butterflies fail to adapt to new host plants. Further, our results support the value of conserving traditional extensive pasture use as a promoter of host plant and, hence, butterfly richness.

中文翻译：

---

高山蝴蝶想飞得更高：物种和群落向上移动的速度比寄主植物快

尽管昆虫食草动物和植物有时具有很强的相互依赖性，但通常是孤立地研究个体类群对加速气候变化的反应。因此，忽略了可能限制物种追踪其首选气候生态位的生物相互作用。在这里，我们选择蝴蝶作为食草昆虫的突出代表，以研究温度变化的影响及其幼虫寄主植物在德国阿尔卑斯山沿 1.4 公里海拔梯度的分布。根据 2009 年的抽样协议，我们在 2019 年的整个生长季节重新访问了 33 个草地。我们通过在每个地块上重复横断面行走来量化蝴蝶丰度和丰富度的变化，并理清了当地评估温度、场地管理、以及这些模式下幼虫和成虫食物资源的可用性。此外，我们还确定了群落和物种水平上蝴蝶和寄主植物的海拔范围变化。比较两个采样年（2009 年和 2019 年），我们发现蝴蝶丰度严重下降，蝴蝶沿海拔梯度明显向上移动。我们检测到物种丰富度峰值、群落组成和物种水平的变化，其中山区物种的变化特别强烈。相比之下，寄主植物几乎没有任何变化，既不与物种丰富度有关，也不与个别物种的变化有关。此外，温度和寄主植物丰富度是蝴蝶丰富度的主要驱动因素，温度变化最好地解释了丰富度随时间的变化。我们得出结论，寄主植物尚未阻碍蝴蝶物种和群落向上迁移。然而，如果蝴蝶不能适应新的寄主植物，蝴蝶和寄主植物转变之间的不匹配可能会成为这种非常密切的植物-食草动物关系的问题，尤其是在高海拔地区。此外，我们的结果支持保护传统粗放牧场作为寄主植物促进剂的价值，从而促进蝴蝶的丰富度。