Evolution of Metabolic Diversity in Animals

动物在能量消耗、生产能力和代谢率方面存在巨大差异。物种的代谢率因其生活方式和栖息地的不同而不同，而进化过程塑造了这些差异。我的研究着眼于为什么以及如何在动物体内进化代谢率以及潜在的生理和生化特性。这项拟议研究的第一个目标将集中在能源生产中涉及的细胞过程。不仅动物的能量产生速率在进化，而且用于产生能量的燃料也因物种而异。蜜蜂和黄蜂等昆虫被认为是糖分专家，但我们最近发现了一种异常高的能力，可以将氨基酸脯氨酸作为产生能量的燃料。一些物种是如何以及为什么进化出利用脯氨酸的能力尚不清楚。为了测试Pro是否是熊蜂飞行的重要燃料，我们将控制含有和不含有Pro的花蜜饮食，并通过抑制参与Pro代谢的中心酶来进行操作。此外，通过比较具有不同生活史策略的蜜蜂和黄蜂的物种，我们将解决脯氨酸是否是越冬期间的一种能源。此外，这种方法还将测试产生大量热量的物种是否使用了更高效的代谢燃料来产生热量。第二个目标将测试动物的大小如何驱动代谢率和潜在特征的进化。在昆虫中，身体和翅膀的大小影响翼拍频率和飞行肌肉收缩速度，这解释了代谢率的差异。为了了解动物的生理特性如何与身体质量和翅膀大小共同进化，我计划使用翅膀比例不同的果蝇。首先，由于发育过程中环境条件的影响，苍蝇的大小和机翼比例可能会有很大的变化，并将研究其对飞行代谢率、飞行性能和肌肉功能的影响。接下来，将进行人工选择实验，以进化出翅膀比例更大和更小的苍蝇。这项实验将可以确定代谢率、飞行能力和肌肉功能是如何共同进化的。我们将利用育种实验和数量遗传学分析工具来确定所研究性状的遗传基础。这项工作将一起阐明动物对能量的利用和产生是如何进化的。拟议的研究将涉及至少五名研究生和超过15名本科生，他们将接受使用进化生物学分析工具进行的代谢生理学培训。

Animals vary tremendously in their energy use and production capacity, their metabolic rate. The metabolic rate of species differs depending on their lifestyle and habitat, and evolutionary processes shape these differences. My research looks at why and how metabolic rate, and the underlying physiological and biochemical properties, evolve in animals. A first objective of the proposed research will focus on the cellular processes involved in energy production. Not only rates of energy production evolve in animals, but the fuels are used to produce energy also differ across species. Insects such as bees and wasps are thought to be sugar specialists, but we recently found an unusually high capacity to use the amino acid proline as a fuel to produce energy. How and why some species evolved the ability to use proline is unknown. To test whether proline is a substantial fuel used for flight in bumblebees, we will manipulate nectar diets with and without proline, and by inhibiting the central enzyme involved in proline metabolism. Furthermore, by comparing species of bees and wasps with diverse life-history strategies, we will address if proline is an energy source during overwintering. Also, this approach will test if species that generate a large amount of heat are doing so using metabolic fuels more efficient at heat production. A second objective will test how the size of animals drives the evolution of metabolic rate and underlying traits. In insects, body and wing size influence wingbeat frequency and flight muscle contraction rate, explaining differences in metabolic rate. To understand how the physiological properties of animals co-evolve with body mass and wing size, I plan on using fruit flies that differ in wing proportions. First, fly size and wing proportions can vary largely due to the influence of environmental conditions during development, and the consequences on flight metabolic rate, flight performance and muscle function will be studied. Next, artificial selection experiments will be conducted to evolve flies with larger and smaller wing proportions. This experiment will allow determining how metabolic rate, flight performance and muscle function co-evolve. We will determine the genetic basis of the traits studied by using breeding experiments and quantitative genetics analytical tools. Together this work will clarify how the use and production of energy evolve in animals. The proposed studies will involve at least five graduate students and over 15 undergraduates that will be trained in metabolic physiology using evolutionary biology analytical tools.