Ecological traits related to pace of life, such as foraging strategies and activity levels, influence daily energy expenditure (DEE) and can affect fitness. A fast pace of life tends to be supported by high-energy aerobic activity and is positively correlated with high DEE and basal and maximal metabolic rates in some endotherms. Given that maximal capacities for exercise and thermogenesis are both functions of aerobic muscle output and are often positively correlated with each other, high-energy aerobic lifestyles might be associated with high aerobic capacities, which would be expected to produce high thermogenic capacities as a side effect. We tested whether the high-energy aerial insectivore lifestyle in swallows is correlated with elevated basal and maximal thermogenic metabolic rates. We measured basal (BMR) and summit (Msum = maximum cold-induced metabolic rate) metabolic rates in 6 species of swallows (Hirundinidae) and combined these data with literature data for additional swallows (n = 10 for BMR; n = 8 for Msum) and non-aerial insectivore birds (n = 215 for BMR; n = 64 for Msum) to address the hypothesis that swallows have higher BMR and Msum than non-aerial insectivores. BMR in swallows was significantly higher than for non-aerial insectivore birds for phylogenetically adjusted analyses after correcting for body mass and region of origin (tropical vs. temperate). In contrast, Msum did not differ significantly between swallows and non-aerial insectivores. Thermogenic scope (Msum – BMR), however, was lower in tropical non-aerial insectivore birds compared with tropical swallows and temperate birds. This suggests that the aerial insectivore lifestyle elevates maintenance costs, but maximum thermogenic capacities are not clearly upregulated, despite tropical swallows having higher thermogenic scope than tropical non-aerial insectivores. These data suggest that the high-energy aerial insectivore lifestyle does not produce strong thermogenic side effects in swallows.

中文翻译：

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燕子的高能空中食虫生活方式不会产生明显的产热副作用

与生活节奏相关的生态特征，例如觅食策略和活动水平，会影响每日能量消耗 (DEE) 并可能影响健康。快节奏的生活往往受到高能量有氧运动的支持，并且与一些吸热体中的高 DEE 以及基础和最大代谢率呈正相关。鉴于运动和产热的最大能力都是有氧肌肉输出的功能，并且通常彼此正相关，高能量的有氧生活方式可能与高有氧能力相关，预计会产生高产热能力作为副作用. 我们测试了燕子的高能量空中食虫生活方式是否与升高的基础和最大产热代谢率相关。我们测量了 6 种燕子（Hirundinidae）的基础（BMR）和峰值（Msum = 最大冷诱导代谢率）代谢率，并将这些数据与其他燕子的文献数据相结合（BMR 为 n = 10；Msum 为 n = 8 ）和非空中食虫鸟类（BMR n = 215；Msum n = 64）来解决燕子比非空中食虫动物具有更高 BMR 和 Msum 的假设。在校正体重和起源区域（热带与温带）后，燕子的 BMR 显着高于非空中食虫鸟类的系统发育调整分析。相比之下，燕子和非空中食虫动物之间的 Msum 没有显着差异。然而，与热带燕子和温带鸟类相比，热带非空中食虫鸟类的产热范围（Msum - BMR）较低。这表明空中食虫动物的生活方式提高了维护成本，但最大产热能力并未明显上调，尽管热带燕子的产热范围高于热带非空中食虫动物。这些数据表明，高能空中食虫生活方式不会对燕子产生强烈的产热副作用。