Evolution and consequences of endothermy in fishes
Evolution and consequences of endothermy in fishes
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DOI：
10.1086/423743
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发表时间：
2004-11-01
影响因子：
1.6
通讯作者：
Graham, JB
中科院分区：
文献类型：
--
作者：
Dickson, KA;Graham, JB
局部恒温，即通过血管逆流热交换器来保存代谢热，以提高慢抽搐运动肌肉、眼睛和大脑或内脏的温度，在包括蓝鳍鲨、长嘴鱼和金枪鱼在内的几个鱼类谱系中独立进化而来。它们都是大型的、活跃的、高能量需求的远洋物种，它们进行长距离迁徙，并在水柱内垂直移动，因此会遇到一系列的水温。在总结了鱼类的恒温现象的基础上，通过对恒温鱼类和异温鱼类的系统发育比较，分析了鱼类的两大优势，即热生态位扩张和有氧游泳性能增强。热生态位的扩展是通过将吸热特征映射到系统发育上，并结合现存物种的热生态位信息、化石记录和吸热鱼类辐射时期的古海洋条件来支持的。然而，很难证明生态位扩张需要恒温动物，而在温跃层以下反复潜水需要恒温动物以外的适应。尽管提高慢收缩、氧化运动肌肉温度的趋同进化表明，这一特征具有选择优势，但将金枪鱼与其异温姊妹物种（鲭鱼和鲣鱼）进行比较，并不能直接支持恒温会提高有氧游泳速度、慢氧化肌肉力量或能量效率的假设。恒温动物与较高的标准代谢率有关，这可能是由于这些高性能鱼类需要高有氧能力来同时进行许多有氧活动。较高的标准代谢率表明，恒温动物的好处可能被大量的能量消耗所抵消。
Regional endothermy, the conservation of metabolic heat by vascular countercurrent heat exchangers to elevate the temperature of the slow-twitch locomotor muscle, eyes and brain, or viscera, has evolved independently among several fish lineages, including lamnid sharks, billfishes, and tunas. All are large, active, pelagic species with high energy demands that undertake long-distance migrations and move vertically within the water column, thereby encountering a range of water temperatures. After summarizing the occurrence of endothermy among fishes, the evidence for two hypothesized advantages of endothermy in fishes, thermal niche expansion and enhancement of aerobic swimming performance, is analyzed using phylogenetic comparisons between endothermic fishes and their ectothermic relatives. Thermal niche expansion is supported by mapping endothermic characters onto phylogenies and by combining information about the thermal niche of extant species, the fossil record, and paleoceanographic conditions during the time that endothermic fishes radiated. However, it is difficult to show that endothermy was required for niche expansion, and adaptations other than endothermy are necessary for repeated diving below the thermocline. Although the convergent evolution of the ability to elevate slow-twitch, oxidative locomotor muscle temperatures suggests a selective advantage for that trait, comparisons of tunas and their ectothermic sister species ( mackerels and bonitos) provide no direct support of the hypothesis that endothermy results in increased aerobic swimming speeds, slow-oxidative muscle power, or energetic efficiency. Endothermy is associated with higher standard metabolic rates, which may result from high aerobic capacities required by these high-performance fishes to conduct many aerobic activities simultaneously. A high standard metabolic rate indicates that the benefits of endothermy may be offset by significant energetic costs.