Trade-offs, limits to adaptation, and multiple solutions: rules elucidated by selective breeding for high activity levels

该项目的重点是了解生物体如何在不同活动的能量分配中进行权衡，以及如何发展多种解决方案来增强运动活动。生物多样性不仅包括物种的数量，还包括它们所表现出的功能多样性。生物体以各种方式工作，并经常表现出权衡和多种解决方案。权衡的一个例子是产生的后代数量和个体后代大小之间的负相关关系，这在许多植物和动物群体中都有记载。这种权衡通常归因于可用于繁殖的能量总量的限制。在飞行进化的各种方式中，多种解决方案是显而易见的（例如，鸟类与蝙蝠）。本研究项目在一项新实验的背景下解决了这两种现象，该实验涉及对家鼠进行高自愿运动水平的选择性育种。两个假设将被测试：(1)选择高活动与终生生殖成功率的降低有关，代表了运动活动和健康之间的权衡；(2)在高活动小鼠系中进化的平均跑步速度和持续时间之间的权衡反映在其肌肉组织特征的相应差异上。这个项目将有助于阐明生物多样性的基本性质。研究结果将在科学出版物上发布，维基百科页面将被创建和更新。开发生态与进化生理学本科课程的在线开放教育资源版本。该项目将在协作、综合和跨学科的研究环境中对研究生和本科生进行培训。为了增加参与和多样性，将招收来自代表性不足群体和教育或经济背景不利的学生。权衡取舍和多种解决方案是生命固有的，似乎是生物多样性随时间变化的大量基础。然而，很少有研究使用实验进化来解决这些问题。拟议的研究将在模型生物（实验室家鼠）中使用高运动活动的选择来阐明运动进化过程中的权衡和多种解决方案。由于运动活动是动物生活史的关键组成部分，这些研究的结果应该提供对一般原理的见解。这项研究将利用一种独特的资源，包括四个重复系的高跑者小鼠，这些小鼠已经被选择性地培育了90多代，用于自主运动活动，另外四个系作为非选择的对照组。目的1将测试所选品系的终生繁殖成功率是否降低，以及这种权衡是否在重复品系中以不同的方式表现出来（例如，产仔数减少与生殖寿命缩短）。目标2将测试肌肉功能的权衡是否隐含在平均跑步速度和持续时间之间的权衡，这在四个选定的线路中已经进化，以及是否涉及肌肉表现水平的多种解决方案。其他研究人员将可以使用这些鼠标系，正在开发的在线课程材料和维基百科内容将广泛传播。一些本科生和研究生将从传统上在科学领域代表性不足的群体中招募，参与这项研究。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project focuses on understanding how organisms make trade-offs in energy allocation to different activities and how multiple solutions to enhance locomotor activity may evolve. Biological diversity encompasses not only numbers of species but the functional diversity that they exhibit. Organisms work in a variety of ways, and often exhibit trade-offs and multiple solutions. One example of a trade-off is the negative relationship between the number of offspring produced and the size of individual offspring, as documented in many groups of plants and animals. This trade-off is often attributed to a constraint on the total amount of energy available for reproduction. Multiple solutions are apparent in the various ways that flight has evolved (e.g., birds versus bats). This research project addresses both of these phenomena in the context of a novel experiment that involves selective breeding for high voluntary levels of exercise in house mice. Two hypotheses will be tested: (1) selection for high activity is associated with reductions in lifetime reproductive success, representing a trade-off between locomotor activity and fitness, and (2) the trade-off between average running speed and duration that has evolved among the high-activity mouse lines is reflected in corresponding differences in characteristics of their muscle tissues. The project will help to elucidate the fundamental nature of biodiversity. The results will be disseminated in scientific publications and Wikipedia pages will be created and updated. An online Open Educational Resource version of Ecological and Evolutionary Physiology, an undergraduate course, will be developed. This project will involve training for both graduate students and undergraduates in a collaborative, integrative, and cross-disciplinary research setting. To increase participation and diversity, students from underrepresented groups and educationally or economically disadvantaged backgrounds will be recruited.Trade-offs and multiple solutions are inherent to life and appear to underlie a substantial amount of the variation in biodiversity over time. However, few studies have used experimental evolution to address these topics. The proposed research will use selection for high locomotor activity, in a model organism (laboratory house mice), to elucidate trade-offs and multiple solutions during locomotor evolution. Because locomotor activity is a key component of the life history of animals, results of these studies should provide insight into general principles. The research will take advantage of a unique resource comprising four replicate lines of High Runner mice that have been selectively bred for more than 90 generations for voluntary locomotor activity, and an additional four lines that serve as non-selected Controls. Aim 1 will test for reduced lifetime reproductive success in the selected lines and whether this trade-off manifests in different ways in the replicate lines (e.g., reduced litter size vs. reduced length of reproductive lifespan). Aim 2 will test whether trade-offs in muscle function underlie the trade-off between average running speed and duration that has evolved among the four selected lines, and if multiple solutions at the level of muscle performance are involved. The mouse lines will be made available to other researchers, and the online course materials and Wikipedia content to be developed will be broadly disseminated. Several undergraduate and graduate students, recruited from groups traditionally under-represented in science, will participate in the research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.