The consequences of climate change for biogeographic range dynamics depend on the spatial scales at which climate influences focal species directly and indirectly via biotic interactions. An overlooked question concerns the extent to which microclimates modify specialist biotic interactions, with emergent properties for communities and range dynamics. Here, we use an in-field experiment to assess egg-laying behaviour of a range-expanding herbivore across a range of natural microclimatic conditions. We show that variation in microclimate, resource condition and individual fecundity can generate differences in egg-laying rates of almost two orders of magnitude in an exemplar species, the brown argus butterfly (Aricia agestis). This within-site variation in fecundity dwarfs variation resulting from differences in average ambient temperatures among populations. Although higher temperatures did not reduce female selection for host plants in good condition, the thermal sensitivities of egg-laying behaviours have the potential to accelerate climate-driven range expansion by increasing egg-laying encounters with novel hosts in increasingly suitable microclimates. Understanding the sensitivity of specialist biotic interactions to microclimatic variation is, therefore, critical to predict the outcomes of climate change across species' geographical ranges, and the resilience of ecological communities.

气候变化对生物地理范围动态的影响取决于气候通过生物相互作用直接和间接影响重点物种的空间尺度。一个被忽视的问题是微气候在多大程度上改变了专业的生物相互作用，以及群落和范围动态的新兴特性。在这里，我们使用现场实验来评估范围扩大的食草动物在一系列自然小气候条件下的产卵行为。我们表明，小气候、资源条件和个体繁殖力的变化可以在示例物种棕色阿格斯蝴蝶 ( Aricia agetis ) 中产生几乎两个数量级的产卵率差异。）。这种繁殖力的场内变化使由种群间平均环境温度差异引起的变化相形见绌。尽管较高的温度并没有减少对处于良好状态的寄主植物的雌性选择，但产卵行为的热敏感性有可能通过在越来越合适的小气候中增加与新宿主的产卵相遇来加速气候驱动的范围扩大。因此，了解专业生物相互作用对小气候变化的敏感性对于预测跨物种地理范围的气候变化结果以及生态群落的恢复力至关重要。