Section of Conservation Biology, Department of Environmental Sciences, University of Basel, St. Johanns-Vorstadt 10, CH-4056, Basel, Switzerland; DSI-NRF Centre of Excellence for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.
School of Biological Sciences, Monash University, Victoria, 3800, Australia.
J Therm Biol. 2021 Oct;101:103106. doi: 10.1016/j.jtherbio.2021.103106. Epub 2021 Sep 22.
Thermal traits are frequently used to explain variation in species distributions, abundance, and sensitivity to climate change. Due to their utility and ease of measurement, critical thermal limits in particular have proliferated across the ecophysiological literature. Critical limit assays can, however, have deleterious or even lethal effects on individuals and there is growing recognition that intermediate metrics of performance can provide a further, nuanced understanding of how species interact with their environments. Meanwhile, the scarcity of data describing sub-critical or voluntary limits, which have been proposed as alternatives to critical limits and can be collected under less extreme conditions, reduces their value in comparative analyses and broad-scale syntheses. To overcome these limitations and determine if sub-critical limits are viable proxies for upper and lower critical thermal limits we measured and compared the critical and sub-critical thermal limits of 2023 ants representing 51 species. Sub-critical limits in isolation were a satisfactory linear predictor for both individual and species critical limits and when species identity was also considered there were substantial gains in variance explained. These gains indicate that a species-specific conversion factor can further improve estimates of critical traits using sub-critical proxies. Sub-critical limits can, therefore, be integrated into broader syntheses of critical limits and confidently used to calculate common ecological metrics, such as warming tolerance, so long as uncertainty in estimates is explicitly acknowledged. Although lower thermal traits exhibited more variation than their upper counterparts, the stronger phylogenetic signal of lower thermal traits indicates that appropriate conversions for lower thermal traits can be inferred from congenerics or other closely related taxa.
热特性通常用于解释物种分布、丰度和对气候变化的敏感性的变化。由于其效用和易于测量，特别是关键热极限在生态生理学文献中大量涌现。然而，临界极限测定法可能对个体产生有害甚至致命的影响，越来越多的人认识到，性能的中间指标可以进一步深入了解物种与环境的相互作用。与此同时，描述亚临界或自愿极限的数据稀缺，这些极限被提议作为临界极限的替代品，可以在不那么极端的条件下收集，这降低了它们在比较分析和广泛综合中的价值。为了克服这些限制，并确定亚临界极限是否可以替代上临界和下临界热极限，我们测量并比较了代表 51 个物种的 2023 种蚂蚁的临界和亚临界热极限。单独的亚临界极限是个体和物种临界极限的令人满意的线性预测因子，当同时考虑物种身份时，解释方差的幅度有很大的提高。这些收益表明，特定物种的转换因子可以使用亚临界代理进一步提高临界特征的估计值。因此，只要明确承认估计值的不确定性，亚临界极限就可以整合到更广泛的临界极限综合分析中，并可用于计算常见的生态指标，如变暖耐受性。虽然较低的热特性表现出比其较高特性更多的变化，但较低热特性的更强的系统发育信号表明，适当的较低热特性的转换可以从同属种或其他密切相关的类群中推断出来。
