Determining how species thermal limits correlate with climate is important for understanding biogeographic patterns and assessing vulnerability to climate change. Such analyses need to consider thermal gradients at multiple spatial scales. Here we relate thermal traits of rainforest ants to microclimate conditions from ground to canopy (microgeographic scale) along an elevation gradient (mesogeographic scale) and calculate warming tolerance to assess climate change vulnerability in the Australian Wet Tropics Bioregion. We test the thermal adaptation and thermal niche asymmetry hypotheses to explain interspecific patterns of thermal tolerance at these two spatial scales. We tested cold tolerance (CT_min), heat tolerance (CT_max), and calculated thermal tolerance range (CT_range), using ramping assays for 74 colonies of 40 ant species collected from terrestrial and arboreal habitats at lowland and upland elevation sites and recorded microclimatic conditions for one year. Within sites, arboreal ants were exposed to hotter microclimates and on average had a 4.2°C (95% CI: 2.7–5.6°C) higher CT_max and 5.3°C (95% CI: 3.5–7°C) broader CT_range than ground-dwelling ants. This pattern was consistent across the elevation gradient, whether it be the hotter lowlands or the cooler uplands. Across elevation, upland ants could tolerate significantly colder temperatures than lowland ants, whereas the change in CT_max was less pronounced, and CT_range did not change over elevation. Differential exposure to microclimates, due to localized niche preferences, drives divergence in CT_max, while environmental temperatures along the elevation gradient drive divergence in CT_min. Our results suggest that both processes of thermal adaptation and thermal niche asymmetry are at play, depending on the spatial scale of observation, and we discuss potential mechanisms underlying these patterns. Despite the broad thermal tolerance range of arboreal rainforest ants, lowland arboreal ants had the lowest warming tolerance and may be most vulnerable to climate change.

中文翻译：

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树栖性推动了热带雨林蚂蚁的耐热性，而海拔则推动了热带雨林蚂蚁的耐寒性

确定物种热极限如何与气候相关对于了解生物地理模式和评估气候变化的脆弱性非常重要。此类分析需要考虑多个空间尺度上的热梯度。在这里，我们将热带雨林蚂蚁的热特性与沿海拔梯度（中地理尺度）从地面到树冠（微地理尺度）的小气候条件联系起来，并计算变暖耐受性以评估澳大利亚湿热带生物区的气候变化脆弱性。我们测试了热适应和热生态位不对称假设，以解释这两个空间尺度上的种间耐热性模式。我们测试了耐寒性 (CT _min )、耐热性 (CT _max ) 和计算的耐热性范围 (CT_range )，对从低地和高地海拔地点的陆地和树栖栖息地收集的 40 种蚂蚁的 74 个菌落进行斜坡分析，并记录一年的小气候条件。在场地内，树栖蚂蚁暴露在更热的小气候中，平均 CT_最大值高 4.2°C (95% CI: 2.7–5.6°C)，CT_范围更宽 5.3°C (95% CI: 3.5–7°C)比地栖蚂蚁。这种模式在海拔梯度上是一致的，无论是较热的低地还是较冷的高地。在整个海拔高度，高地蚂蚁比低地蚂蚁可以忍受明显更冷的温度，而 CT _max的变化不太明显，CT_范围没有随海拔变化。由于局部生态位偏好，对微气候的不同暴露导致 CT _{max 的}差异，而沿海拔梯度的环境温度驱动 CT _{min 的}差异。我们的研究结果表明，热适应和热生态位不对称的过程都在起作用，这取决于观察的空间尺度，我们讨论了这些模式背后的潜在机制。尽管树栖雨林蚂蚁的耐热范围很广，但低地树栖蚂蚁的变暖耐受性最低，可能最容易受到气候变化的影响。