Decreasing Phanerozoic extinction intensity as a consequence of Earth surface oxygenation and metazoan ecophysiology
Decreasing Phanerozoic extinction intensity as a consequence of Earth surface oxygenation and metazoan ecophysiology
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DOI：
10.1073/pnas.2101900118
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发表时间：
2021-10
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影响因子：
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通讯作者：
R. Stockey;A. Pohl;A. Ridgwell;S. Finnegan;E. Sperling
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作者：
R. Stockey;A. Pohl;A. Ridgwell;S. Finnegan;E. Sperling
在整个地质时期，灭绝率的下降是海洋动物化石记录中一个公认但神秘的特征。我们假设这一趋势主要是由大气和海洋氧合的长期变化驱动的，因为生理学原理预测，在大气氧合有限的地质时期，海洋动物更容易受到海洋变暖的影响。我们在全球海洋学尺度上通过结合海洋地球化学和动物生理学模型来测试这一点。我们发现，大气中的氧气施加一阶控制模拟的海洋动物灭绝的脆弱性，突出其可能的重要性，通过地质时间控制灭绝的趋势。海洋动物的背景灭绝率在整个地质时期的下降是一个确定的，但无法解释的古生代化石记录的特点。越来越多的人认为，直到古生代中期，海洋和大气的含氧量才达到接近现代的水平，这与普遍较低的灭绝率相吻合。生理学理论为我们提供了这两个观测之间可能的因果关系预测氧气和温度对有氧呼吸的协同影响会使海洋动物在有限的表面氧合期间更容易受到海洋变暖事件的影响。在这里，我们评估的假设，即表面氧化的变化施加了一阶控制灭绝率通过中生代使用相结合的地球系统和生态生理建模方法。我们发现，虽然大陆的配置，海洋中生物碳泵的效率，和初始气候状态都影响模拟的生物多样性损失的幅度在模拟变暖事件，大气中的氧气是灭绝脆弱性的主要预测因子，与代谢栖息地的生存能力和全球生态生理型灭绝表现出拐点约40%，目前的大气中的氧气。鉴于这是广泛的上限估计早古生代的氧水平，我们的研究结果是一致的相对频率的高震级灭绝事件（特别是那些不包括在典型的大五质量灭绝）早古生代有限的早古生代氧和温度依赖性缺氧反应的直接后果。
Significance The decline in extinction rates through geologic time is a well-established but enigmatic feature of the marine animal fossil record. We hypothesize that this trend is driven largely by secular changes in the oxygenation of the atmosphere and oceans, as physiological principles predict that marine animals would have been more vulnerable to ocean warming during intervals of geological time with limited atmospheric oxygenation. We test this at a global oceanographic scale by combining models of ocean biogeochemistry and animal physiology. We show that atmospheric oxygen exerts a first-order control on the simulated extinction vulnerability of marine animals, highlighting its likely importance in controlling extinction trends through geologic time. The decline in background extinction rates of marine animals through geologic time is an established but unexplained feature of the Phanerozoic fossil record. There is also growing consensus that the ocean and atmosphere did not become oxygenated to near-modern levels until the mid-Paleozoic, coinciding with the onset of generally lower extinction rates. Physiological theory provides us with a possible causal link between these two observations—predicting that the synergistic impacts of oxygen and temperature on aerobic respiration would have made marine animals more vulnerable to ocean warming events during periods of limited surface oxygenation. Here, we evaluate the hypothesis that changes in surface oxygenation exerted a first-order control on extinction rates through the Phanerozoic using a combined Earth system and ecophysiological modeling approach. We find that although continental configuration, the efficiency of the biological carbon pump in the ocean, and initial climate state all impact the magnitude of modeled biodiversity loss across simulated warming events, atmospheric oxygen is the dominant predictor of extinction vulnerability, with metabolic habitat viability and global ecophysiotype extinction exhibiting inflection points around 40% of present atmospheric oxygen. Given this is the broad upper limit for estimates of early Paleozoic oxygen levels, our results are consistent with the relative frequency of high-magnitude extinction events (particularly those not included in the canonical big five mass extinctions) early in the Phanerozoic being a direct consequence of limited early Paleozoic oxygenation and temperature-dependent hypoxia responses.