Greenberg Dan A, Palen Wendy J
Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6.
Proc Biol Sci. 2021 Feb 24;288(1945):20202273. doi: 10.1098/rspb.2020.2273. Epub 2021 Feb 17.
Concerns over the consequences of global climate change for biodiversity have spurred a renewed interest in organismal thermal physiology. However, temperature is only one of many environmental axes poised to change in the future. In particular, hydrologic regimes are also expected to shift concurrently with temperature in many regions, yet our understanding of how thermal and hydration physiology jointly affect performance and fitness is still limited for most taxonomic groups. Here, we investigated the relationship between functional performance, hydration state and temperature in three ecologically distinct amphibians, and compare how temperature and water loss can concurrently limit activity under current climate conditions. We found that performance was maintained across a broad range of hydration states in all three species, but then declines abruptly after a threshold of 20-30% mass loss. This rapid performance decline was accelerated when individuals were exposed to warmer temperatures. Combining our empirical hydrothermal performance curves with species-specific biophysical models, we estimated that dehydration can increase restrictions on species' activity by up to 60% compared to restriction by temperature alone. These results illustrate the importance of integrating species' hydration physiology into forecasts of climate vulnerability, as omitting this axis may significantly underestimate the effects of future climate change on Earth's biological diversity.
对全球气候变化对生物多样性影响的担忧激发了人们对生物热生理学的新兴趣。然而，温度只是未来可能发生变化的众多环境因素之一。特别是，在许多地区，水文状况预计也会随着温度同时发生变化，然而对于大多数分类群来说，我们对热生理学和水合生理学如何共同影响生物性能和适应性的理解仍然有限。在此，我们研究了三种生态特征不同的两栖动物的功能性能、水合状态和温度之间的关系，并比较了在当前气候条件下温度和水分流失如何同时限制其活动。我们发现，所有这三个物种在广泛的水合状态范围内都能维持性能，但在体重损失达到20%-30%的阈值后，性能会突然下降。当个体暴露在较高温度下时，这种性能的快速下降会加速。将我们的经验性水热性能曲线与特定物种的生物物理模型相结合，我们估计，与仅受温度限制相比，脱水会使对物种活动的限制增加高达60%。这些结果说明了将物种的水合生理纳入气候脆弱性预测的重要性，因为忽略这一因素可能会显著低估未来气候变化对地球生物多样性的影响。
