How does sequential acquisition of nutritional resources modulate allocation decisions? A whole-organism perspective on life history tradeoffs

自然界中生物体可获得的营养资源往往是有限的。分配给一个性状的资源不能用于其他性状，从而导致资源分配的权衡。这种权衡是我们理解所有动物和植物的生态学和进化的基础。然而，关于权衡的经验证据却出奇地难以获得。这在一定程度上是由于与量化生物体获得的营养成分和数量以及这些营养成分如何在生物体的整个生命中分布有关的挑战。本研究将探讨普通卷心菜白蝴蝶（Pieris rapae）如何在飞行和繁殖力这两个关键功能之间获取和分配营养。这项研究特别新颖，它利用了营养生理学的最新技术进步，直接追踪特定营养输入（例如氨基酸和碳水化合物）的影响，逐秒逐秒地跟踪蝴蝶孵化、生长、扩散和繁殖的过程。这项研究的结果将有助于解决理解权衡的一个大谜团，为什么我们总是看不到预测存在的权衡？该项目还将支持一个名为“昆虫发现”（Insect Discovery）的推广项目，该项目利用卷心菜白蝴蝶等昆虫向K-12学生教授生物学。利用在COVID-19关闭期间吸取的经验教训，这笔赠款将开发在线内容，并将虚拟教学经验扩展到亚利桑那州各地服务不足的农村和部落学校。资源分配的权衡之所以发生，是因为生物体在其一生中只能获得有限的资源，分配给一个性状的资源不能用于其他性状。由于它们的重要性，权衡已经被研究了50多年，导致了一个相当强大的理论理解。然而，令人惊讶的是，在自然界中往往找不到权衡，即使它们被预测存在。大多数关于权衡的研究都是在一个特定的时刻测量特征。然而，资源的获取和分配是一个动态的过程，发生在整个生物体的生命周期。现在分配的资源可能只会在以后的权衡中体现出来。本研究将结合营养生态学和尖端稳定同位素示踪方法，确定特定营养物质和营养混合物在所有生命阶段内和整个生命阶段的获取和分配之间的相互作用，以了解与重要权衡（飞行与繁殖力）相关的决策过程。具体来说，这个项目将解决：1)取食花蜜能改善飞行繁殖力的权衡吗？2)飞行-繁殖力的权衡如何影响雌性获得额外资源的能力？3)不同的资源货币如何调节“逃离-繁殖力”权衡的表达？4)卵子中的营养供给如何介导代际间的飞行繁殖力权衡？通过在一个完整的生命周期中，从一个鸡蛋到另一个鸡蛋，追踪单个营养物质，进化生物学中的一个令人困惑的难题将得到解决：为什么我们没有在预期的时候看到性状之间的权衡？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。

Nutritional resources available to organisms are often limited in nature. Resources allocated to one trait are not available to other traits resulting in resource allocation tradeoffs. Such tradeoffs are at the foundation of our understanding of the ecology and evolution of all animals and plants. However, empirical evidence for tradeoffs has been surprisingly difficult to obtain. This is in part due to challenges associated with quantifying which and how much nutrients organisms obtain, and how these nutrients are distributed across the organism’s life. This study will examine how the common cabbage-white butterfly (Pieris rapae) obtains and allocates nutrients between two critical functions, flight vs. fecundity. This research is particularly novel in taking advantage of the most recent technological advances in nutritional physiology to directly trace the effects of specific nutrient inputs (e.g., amino acids and carbohydrates), literally second by second, as this butterfly hatches, grows, disperses, and reproduces. Results of this study will help resolve one of the big mysteries in understanding tradeoffs, why don’t we always see the tradeoffs that are predicted to exist? This project will also support Insect Discovery, an established outreach program that uses insects, like the cabbage-white butterfly, to teach biology to K-12 students. Using lessons learned during the COVID-19 closure, this grant will develop online content and extend the virtual teaching experience to underserved rural and tribal schools around the state of Arizona.Resource allocation tradeoffs occur because organisms can only acquire a finite amount of resources in their lifetimes and resources allocated to one trait are not available to other traits. Because of their importance, tradeoffs have been studied for well over 50 years, leading to a fairly robust theoretical understanding. Surprisingly however, tradeoffs are often not found in nature, even when they are predicted to exist. Most studies of tradeoffs measure traits at a particular instant in time. Yet, resource acquisition and allocation is a dynamic process that occurs throughout an organism’s life cycle. It is possible that resources allocated now will only be manifested in a tradeoff later. This research will integrate approaches from nutritional ecology with cutting-edge stable isotope tracer methodologies to determine the interplay between acquisition and allocation of specific nutrients and nutrient mixtures, both within and across all life stages, to understand the decision making processes associated with an important tradeoff, flight vs. fecundity, in Pieris rapae butterflies. Specifically, this project will address: 1) Can nectar-feeding ameliorate flight-fecundity tradeoffs? 2) How do flight-fecundity tradeoffs influence the ability of females to acquire additional resources? 3) How do different resource currencies modulate the expression of a flight-fecundity tradeoff? 4) How does nutrient provisioning in eggs mediate flight fecundity tradeoffs across generations? By tracking individual nutrients throughout a complete life cycle, egg to egg, a perplexing conundrum in evolutionary biology will be addressed: why don’t we see tradeoffs among traits when they are expected?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.