College of Marine Science, University of South Florida, St Petersburg, FL 33701, USA
School of Oceanography, University of Washington, 1492 NE Boat Street, Seattle, WA 98105, USA.
J Exp Biol. 2020 Jun 16;223(Pt 12):jeb210492. doi: 10.1242/jeb.210492.
The capacity to extract oxygen from the environment and transport it to respiring tissues in support of metabolic demand reportedly has implications for species' thermal tolerance, body size, diversity and biogeography. Here, we derived a quantifiable linkage between maximum and basal metabolic rate and their oxygen, temperature and size dependencies. We show that, regardless of size or temperature, the physiological capacity for oxygen supply precisely matches the maximum evolved demand at the highest persistently available oxygen pressure and this is the critical for the maximum metabolic rate, For most terrestrial and shallow-living marine species, is the current atmospheric pressure, 21 kPa. Any reduction in oxygen partial pressure from current values will result in a calculable decrement in maximum metabolic performance. However, oxygen supply capacity has evolved to match demand across temperatures and body sizes and so does not constrain thermal tolerance or cause the well-known reduction in mass-specific metabolic rate with increasing body mass. The critical oxygen pressure for resting metabolic rate, typically viewed as an indicator of hypoxia tolerance, is, instead, simply a rate-specific reflection of the oxygen supply capacity. A compensatory reduction in maintenance metabolic costs in warm-adapted species constrains factorial aerobic scope and the critical to a similar range, between ∼2 and 6, across each species' natural temperature range. The simple new relationship described here redefines many important physiological concepts and alters their ecological interpretation.
从环境中提取氧气并将其运输到呼吸组织中以支持代谢需求的能力据称对物种的热耐受性、体型、多样性和生物地理学有影响。在这里，我们得出了最大代谢率和基础代谢率与其氧气、温度和大小依赖性之间的定量关系。我们表明，无论大小或温度如何，氧气供应的生理能力都恰好与在最高可维持氧气压力下的最高进化需求相匹配，这是最大代谢率的关键 对于大多数陆地和浅海生物物种， 是当前的大气压力，即 21 kPa。氧气分压从当前值的任何降低都会导致最大代谢性能的可计算降低。然而，氧气供应能力已经进化到适应温度和体型的需求，因此不会限制热耐受性或导致众所周知的随着体重增加而降低比代谢率。静息代谢率的关键氧气压力，通常被视为缺氧耐受性的指标，实际上只是氧气供应能力的一种特定速率反映。在温暖适应物种中，维持代谢成本的补偿性降低限制了有氧范围的因素和关键 值在每个物种的自然温度范围内都相似，在 2 到 6 之间。这里描述的简单新关系重新定义了许多重要的生理概念，并改变了它们的生态解释。
