Department of Integrative Biology, University of California, Berkeley, California, USA.
National Institutes of Health, National Heart, Lung and Blood Institute, Bethesda, Maryland, USA.
J Evol Biol. 2022 Apr;35(4):599-609. doi: 10.1111/jeb.13996. Epub 2022 Mar 7.
Life history and metabolism covary, but the mechanisms and individual traits responsible for these linkages remain unresolved. Dispersal capability is a critical component of life history that is constrained by metabolic capacities for energy production. Conflicting relationships between metabolism and life histories may be explained by accounting for variation in dispersal and maximal metabolic rates. We used female wing-polymorphic sand field crickets, Gryllus firmus, selected either for long wings (LW, flight-capable) or short wings (SW, flightless) to test the hypothesis that selection on dispersal capability drives the evolution of metabolic capacities. While resting metabolic rates were similar, long-winged crickets reached higher maximal metabolic rates than short-winged crickets, resulting in improved running performance. We further provided insight into the mechanisms responsible for covariation between life history and metabolism by comparing mitochondrial content of tissues involved in powering locomotion and assessing the function of mitochondria isolated from long- and short-winged crickets. Our results demonstrated that larger metabolic capacities in long-winged crickets were underpinned by increases in mitochondrial content of dorsoventral flight muscle and enhanced bioenergetic capacities of mitochondria within the fat body, a tissue responsible for fuel storage and mobilization. Thus, selection on flight capability correlates with increases in maximal, but not resting metabolic rates, through modifications of tissues powering locomotion at the cellular and organelle levels. This allows organisms to meet high energetic demands of activity for life history. Dispersal capability should therefore explicitly be considered as a potential factor driving the evolution of metabolic capacities.
生活史和代谢相互关联，但负责这些联系的机制和个体特征仍未得到解决。扩散能力是生活史的一个关键组成部分，受到代谢产生能量能力的限制。代谢和生活史之间的冲突关系可以通过考虑扩散和最大代谢率的变化来解释。我们使用了雌性翼型多态沙蝗， Gryllus firmus，选择长翅（LW，有飞行能力）或短翅（SW，无飞行能力），以检验选择扩散能力是否会驱动代谢能力进化的假说。虽然静息代谢率相似，但长翅蝗虫达到的最大代谢率高于短翅蝗虫，从而提高了奔跑性能。我们通过比较参与运动的组织中线粒体含量，并评估从长翅和短翅蝗虫中分离的线粒体的功能，进一步深入了解了生活史和代谢之间协同进化的机制。我们的研究结果表明，长翅蝗虫更大的代谢能力是由背-腹飞行肌肉中线粒体含量的增加以及脂肪体中线粒体的生物能量能力增强所支撑的，脂肪体是负责燃料储存和动员的组织。因此，飞行能力的选择与最大代谢率而不是静息代谢率的增加相关，这是通过在细胞和细胞器水平上改变为运动提供动力的组织来实现的。这使生物体能够满足生活史活动的高能量需求。因此，扩散能力应被明确视为驱动代谢能力进化的潜在因素。
