Energy management and life history evolution in variable environments

一个人的精力充沛的状态被假设为是其生殖输出的核心影响，但精力充沛的测量通常是在实验室，远离他们的生态进化背景。因此，我的长期目标是了解环境变化如何影响野生动物的能量状态，并塑造野生动物的生殖分配决策。在这个授予周期中，我将完成三个短期目标：（1）确定环境和内在影响对能量获取和同化水平变化的影响，为繁殖做准备;（2）测试两种假设的能量机制，以解释在单一繁殖事件中的繁殖限制;以及（3）揭示繁殖事件之间的关系，解释整个生命周期的最佳能量分配决策。我将使用一个最先进的移动的实验室来表征两个已建立的野生哺乳动物研究系统（落基山地松鼠（RMGSP）和克卢恩红松鼠项目（KRSP））以及一个新的实地研究北极地松鼠（Urocitellus paryii）和实验室小鼠（小家鼠）的圈养研究中的个人的精力充沛的状态。具体来说，我将使用定量磁性身体成分分析仪来测量能量储存（脂肪和瘦体重）和开放流呼吸测量来测量能量使用（代谢率）。在实地项目中，我们将在可量化的环境变化背景下，收集全面普查人口中所有个体的完整生活史数据。在RMGSP中，我们将研究自然和人为的食物资源和天气变化对哥伦比亚地松鼠（U。columbianus）。我们还将收集来自两个不同海拔高度的个体在共同的圈养环境中冬眠期间的详细能量数据。我将通过对野生北极地松鼠进行平行研究来评估这些发现的普遍性。在KRSP中，我们将评估缓存和身体资源变化的决定因素，以及这种变化如何影响红松鼠（Tamiasciurus hudsonicus）繁殖事件内和繁殖事件之间的生殖分配。我们还将使用毛皮减少实验来检验假设，即限制繁殖过程中代谢产生的额外热量会限制产量。在实验室小鼠中，我将研究毛皮减少和热量限制对寿命和生殖输出的交互作用。生殖输出的变化是人口和微进化动力学的核心组成部分，但这种变化的主要贡献者（精力充沛的状态）通常被视为一个“黑箱”。通过打开这个黑匣子，这项研究应该产生重要的基础和应用相关性的结果。

The energetic status of an individual is hypothesized to be a core influence on its reproductive output, but energetic measurements are typically made in laboratories, far removed from their eco-evolutionary context. My long-term goal is therefore to understand how environmental variation influences the energetic statuses of, and shapes the reproductive allocation decisions made by, wild animals. I will meet three short-term objectives over this granting cycle: (1) Determine the environmental and intrinsic influences on variation in levels of energy acquisition and assimilation in preparation for reproduction; (2) Test two hypothesized energetic mechanisms put forward to explain reproductive constraints during a single breeding event; and (3) Uncover relationships between breeding events that explain optimal energy allocation decisions across the lifetime. I will use a state-of-the-art mobile laboratory to characterize the energetic statuses of individuals within two established wild mammal study systems (the Rocky Mountain Ground Squirrel (RMGSP) and Kluane Red Squirrel Projects (KRSP)) as well as a new field study on Arctic ground squirrels (Urocitellus paryii) and a captive study on lab mice (Mus musculus). Specifically, I will use a quantitative magnetic body composition analyzer to measure energy stores (fat and lean mass) and open flow respirometry to measure energy use (metabolic rate). In the field projects, we will collect complete life history data for all individuals in fully censused populations against a backdrop of quantifiable environmental variation. In RMGSP, we will study the influences of natural and manipulated variation in food resources and weather on hibernation profiles and reproductive allocations of Columbian ground squirrels (U. columbianus). We will also collect detailed energetic data during hibernation of individuals from two different elevations in a common, captive environment. I will evaluate the generality of these findings by conducting a parallel study on wild Arctic ground squirrels. In KRSP, we will assess the determinants of variation in cached and on-body resources, and how this variation influences reproductive allocations made within and across breeding events in red squirrels (Tamiasciurus hudsonicus). We will also use a fur reduction experiment to test the hypothesis that limits on dissipating extra metabolically generated heat during reproduction can constrain output. In lab mice, I will study the interactive effects of fur reduction and calorie restriction on longevity and reproductive output. Variation in reproductive output is a central component in both population and microevolutionary dynamics, but a main contributor to this variation (energetic status) is typically treated as a `black-box'. By opening this black box, this research should produce results of both important fundamental and applied relevance.