Climate Warming, Resource Availability, and the Metabolic Meltdown of Ectotherms
Climate Warming, Resource Availability, and the Metabolic Meltdown of Ectotherms
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DOI：
10.1086/705679
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发表时间：
2019-12-01
影响因子：
2.9
通讯作者：
Kingsolver, Joel G.
中科院分区：
文献类型：
--
作者：
Huey, Raymond B.;Kingsolver, Joel G.
气候变暖可能会降低环境资源水平，生长和许多外温动物的健身。在一个经典的实验中，布雷特和他的同事证明了鲑鱼的生长速度明显取决于温度和食物水平。在这里，我们开发了一个简单的生物能量模型，探讨如何固定的温度和食物共同改变净能量增益的热敏感性。该模型采用了不同的热量摄入和代谢的敏感性。在定性协议布雷特的结果，它预测，减少食物摄入量降低生长速度，降低最佳温度的增长，并降低最高温度维持增长（上限热）。因此，在温暖的环境中面临食物摄入量减少的外温动物应该将活动限制在低体温在生物学上可行的时间，但是在一个变暖的世界里，这将迫使外温动物缩短活动时间，从而进一步减少食物摄入量。这种“代谢崩溃”是能量摄入减少、高温下代谢成本加速以及变暖对活动施加限制的结果。接下来，我们扩展了模型，以探索平均环境温度的增加如何改变生长的热敏感性：当食物摄入量减少时，生长的最佳温度和上限温度降低。我们讨论我们的模型的关键假设和警告，以及它的关系，最近的浮游植物模型。这两个模型都表明，如果食物摄入量也减少，气候变暖对外温动物的有害影响将被放大，这要么是因为变暖减少了常备食物资源，要么是因为它限制了觅食时间。
Climate warming may lower environmental resource levels, growth, and fitness of many ectotherms. In a classic experiment, Brett and colleagues documented that growth rates of salmon depended strikingly on both temperature and food levels. Here we develop a simple bioenergetic model that explores how fixed temperatures and food jointly alter the thermal sensitivity of net energy gain. The model incorporates differing thermal sensitivities of energy intake and metabolism. In qualitative agreement with Brett's results, it predicts that decreased food intake reduces growth rates, lowers optimal temperatures for growth, and lowers the highest temperatures sustaining growth (upper thermal limit). Consequently, ectotherms facing reduced food intake in warm environments should restrict activity to times when low body temperatures are biophysically feasible, but-in a warming world-that will force ectotherms to shorten activity times and thus further reduce food intake. This "metabolic meltdown" is a consequence of declining energy intake coupled with accelerating metabolic costs at high temperatures and with warming-imposed restrictions on activity. Next, we extend the model to explore how increasing mean environmental temperatures alter the thermal sensitivity of growth: when food intake is reduced, optimal temperatures and upper thermal limits for growth are lowered. We discuss our model's key assumptions and caveats as well as its relationship to a recent model for phytoplankton. Both models illustrate that the deleterious impacts of climate warming on ectotherms will be amplified if food intake is also reduced, either because warming reduces standing food resources or because it restricts foraging time.