Is hypoxia vulnerability in fishes a by-product of maximum metabolic rate?
Is hypoxia vulnerability in fishes a by-product of maximum metabolic rate?
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DOI：
10.1242/jeb.232520
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发表时间：
2021-07-01
影响因子：
2.8
通讯作者：
Negrete, Benjamin
中科院分区：
文献类型：
--
作者：
Esbaugh, Andrew J.;Ackerly, Kerri L.;Negrete, Benjamin
代谢指数的概念结合代谢数据和已知的热敏感性，估计因子有氧范围的动物在不同的栖息地，这是有价值的理解的代谢需求，限制物种的地理分布。这一概念的一个重要假设是，O-2供应能力（相当于氧消耗率除以环境氧分压：（M）除以dotO（2）/PO 2）在O-2张力高于临界O-2阈值（即，O-2摄取不再能满足代谢需求的PO 2）时是恒定的。这导致了缺氧脆弱性不是一个选择的特征，而是最大代谢率选择的副产品的概念。在这篇评论中，我们探讨这一基本假设是否在鱼类中得到支持。我们提供的证据表明，O-2供应能力是不恒定的，在所有的鱼类，与一些物种表现出在缺氧环境中的O-2供应能力升高。我们进一步讨论了不同的选择压力缺氧和运动为基础的心肺适应鱼类，同时也考虑到缺氧优化的O-2供应能力的代谢指数的概念的影响。
The metabolic index concept combines metabolic data and known thermal sensitivities to estimate the factorial aerobic scope of animals in different habitats, which is valuable for understanding the metabolic demands that constrain species' geographical distributions. An important assumption of this concept is that the O-2 supply capacity (which is equivalent to the rate of oxygen consumption divided by the environmental partial pressure of oxygen: (M) over dotO(2)/PO2) is constant at O-2 tensions above the critical O-2 threshold (i.e. the PO2 where O-2 uptake can no longer meet metabolic demand). This has led to the notion that hypoxia vulnerability is not a selected trait, but a by-product of selection on maximum metabolic rate. In this Commentary, we explore whether this fundamental assumption is supported among fishes. We provide evidence that O-2 supply capacity is not constant in all fishes, with some species exhibiting an elevated O-2 supply capacity in hypoxic environments. We further discuss the divergent selective pressures on hypoxia- and exercise-based cardiorespiratory adaptations in fishes, while also considering the implications of a hypoxia-optimized O-2 supply capacity for the metabolic index concept.