Reconsidering the Oxygen–Temperature Hypothesis of Polar Gigantism: Successes, Failures, and Nuance
Reconsidering the Oxygen–Temperature Hypothesis of Polar Gigantism: Successes, Failures, and Nuance
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重新考虑极地巨人论的氧温度假说：成功、失败和细微差别
DOI：
10.1093/icb/icaa088
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发表时间：
2020
影响因子：
2.6
通讯作者：
Moran, Amy L
中科院分区：
文献类型：
--
作者：
Woods, H Arthur;Moran, Amy L
“极地暖温性”描述了一种地理模式，其中极地海洋中的许多外温动物比它们的温暖水域亲属大。尽管已经提出了许多机制，但有一个想法--氧温假说--受到了极大的关注，因为它来自基本的生物物理学原理，而且非常简单和可检验。低温抑制对氧的代谢需求超过从环境到生物体的氧供应。这创造了更大的氧气供应与需求比率，将极地生物从基于氧气的身体大小限制中释放出来。在这里，我们审查证据支持和反对氧气温度假说。一些数据表明，体型较大的类群生活在接近氧气极限的地方，或者温度升高会挑战氧气输送系统;其他数据没有提供身体大小，温度和氧气充足之间相互作用的证据。我们认为，这些发现可以通过认识到氧-温度假说主要关注氧的被动运动，隐含地忽略了其他重要过程，包括呼吸表面的通气或分布系统的氧内部运输来部分地协调。因此，这一假说可能最有意义地适用于生理系统发育不良的生物体（卵、胚胎、卵块、幼体或没有内外表面通风机制的成体）。最后，大多数对氧温假说的检验都是短期实验。许多生物体可以在短时间内对生理挑战做出有效的反应;然而，这样做的能量成本可能只会在长期内产生影响。因此，我们主张重新关注氧气-温度相互作用的长期研究。
“Polar gigantism” describes a biogeographic pattern in which many ectotherms in polar seas are larger than their warmer-water relatives. Although many mechanisms have been proposed, one idea—the oxygen–temperature hypothesis—has received significant attention because it emerges from basic biophysical principles and is appealingly straightforward and testable. Low temperatures depress metabolic demand for oxygen more than supply of oxygen from the environment to the organism. This creates a greater ratio of oxygen supply to demand, releasing polar organisms from oxygen-based constraints on body size. Here we review evidence for and against the oxygen–temperature hypothesis. Some data suggest that larger-bodied taxa live closer to an oxygen limit, or that rising temperatures can challenge oxygen delivery systems; other data provide no evidence for interactions between body size, temperature, and oxygen sufficiency. We propose that these findings can be partially reconciled by recognizing that the oxygen–temperature hypothesis focuses primarily onpassive movementof oxygen, implicitly ignoring other important processes including ventilation of respiratory surfaces or internal transport of oxygen by distribution systems. Thus, the hypothesis may apply most meaningfully to organisms with poorly developed physiological systems (eggs, embryos, egg masses, juveniles, or adults without mechanisms for ventilating internal or external surfaces). Finally, most tests of the oxygen–temperature hypothesis have involved short-term experiments. Many organisms can mount effective responses to physiological challenges over short time periods; however, the energetic cost of doing so may have impacts that appear only in the longer term. We therefore advocate a renewed focus on long-term studies of oxygen–temperature interactions.