Svensson Erik I, Schou Mads F, Melgar Julian, Waller John, Engelbrecht Anel, Brand Zanell, Cloete Schalk, Cornwallis Charlie K
Department of Biology, Lund University, Lund, Sweden.
Department of Biology, Aarhus University, Aarhus, Denmark.
Evol Lett. 2023 Oct 20;8(2):200-211. doi: 10.1093/evlett/qrad049. eCollection 2024 Apr.
Organisms inhabiting extreme thermal environments, such as desert birds, have evolved spectacular adaptations to thermoregulate during hot and cold conditions. However, our knowledge of selection for thermoregulation and the potential for evolutionary responses is limited, particularly for large organisms experiencing extreme temperature fluctuations. Here we use thermal imaging to quantify selection and genetic variation in thermoregulation in ostriches (), the world's largest bird species that is experiencing increasingly volatile temperatures. We found that females who are better at regulating their head temperatures ("thermoregulatory capacity") had higher egg-laying rates under hotter conditions. Thermoregulatory capacity was both heritable and showed signatures of local adaptation: females originating from more unpredictable climates were better at regulating their head temperatures in response to temperature fluctuations. Together these results reveal that past and present evolutionary processes have shaped genetic variation in thermoregulatory capacity, which appears to protect critical organs, such as the brain, from extreme temperatures during reproduction.
栖息在极端热环境中的生物，比如沙漠鸟类，已经进化出了惊人的适应能力，以便在炎热和寒冷条件下进行体温调节。然而，我们对体温调节选择以及进化反应潜力的了解有限，尤其是对于经历极端温度波动的大型生物。在这里，我们使用热成像技术来量化鸵鸟体温调节的选择和遗传变异，鸵鸟是世界上最大的鸟类物种，正经历着越来越不稳定的温度。我们发现，在较热条件下，更善于调节头部温度（“体温调节能力”）的雌性鸵鸟产卵率更高。体温调节能力具有遗传性，并且显示出局部适应的特征：来自气候更不可预测地区的雌性鸵鸟在应对温度波动时更善于调节头部温度。这些结果共同表明，过去和现在的进化过程塑造了体温调节能力的遗传变异，这种变异似乎在繁殖过程中保护关键器官，如大脑，免受极端温度的影响。
