Reproductive Allocation of Specific Nutrients: The Effects of Foraging, Life History, and Flight

许多生物，包括蝴蝶和其他一些昆虫，其幼虫和成虫的生活期非常不同。生活方式的许多方面，包括食物来源，在不同的生命阶段是不同的。不同物种可获得的成虫食物的质量和数量不同，导致物种之间在成虫和幼虫食物在产卵和成虫生存中的相对重要性或生活史特征上的差异。这些来自不同生命阶段的营养的重要性模式决定了鸡蛋生产的时机和鸡蛋的营养成分。我们有关幼虫和成虫来源的卵的营养分配工作，旨在了解对可能的摄食和繁殖习性组合的限制，以及物种在不同环境中可能持续的情况。我们将利用食物来源稳定的碳同位素比率的自然变化作为工具，追踪用于产卵的营养物质的来源。我们将提出三个假设。第一部分阐述了六种鳞翅目昆虫之间的分配差异，这些鳞翅目昆虫的成虫食物供应和质量自然不同。我们将确定分配给繁殖的营养来源(即幼虫食物与成人食物)是否随成年饲料生态的不同而变化。第二个假设与两个营养库的化学特性有关。这些信息使我们能够了解控制幼虫和成虫在卵中相对使用饲料营养的生理机制。第三种假设探索了生态因素，即花蜜可获得性和飞行时间的变化，可能会影响一个物种的分配模式。同一物种的个体将被饲养在不同的食物供应条件下，并将被诱导每天飞行不同的时间。这些个体的卵的稳定碳同位素组成将被分析，以了解繁殖分配如何与饲养条件和飞行费用相互作用。这项实验允许将我们的结果外推到野外环境中。我们拟议的工作结果将提供关于营养生态、能量代谢和生殖之间的关系的信息。这一信息对蝴蝶和其他昆虫具有特别的实用价值，它们中的许多物种受到威胁，或者是保护生物学的重要指标。然而，更广泛地说，拟议的研究将为进一步研究营养动态和生活史的演变提供重要的概念和经验基础。

Many organisms, including butterflies and some other insects, have very different larval and adult life stages. Many aspects of the life style, including food sources, differ between these life stages. Species differ in the quality and quantity of adult food available to them, resulting in differences among species in the relative importance of adult and larval food in egg production and adult survival, or life history traits. These patterns of importance of nutrients from different life stages determine the timing of egg production, and the nutrient make-up of the egg. Our work on nutrient allocation to eggs from larval and adult sources is aimed at understanding the constraints on possible combinations of feeding and reproductive habits, as well as the likely persistence of species in different environments.We will use natural variation in stable carbon isotope ratios of food sources as a tool for tracing the origin of nutrients used to make eggs. We will address three hypotheses. The first addresses how allocation varies among six species of Lepidoptera that differ naturally in availability and quality of adult food. We will determine if the source of nutrients allocated to reproduction (i.e., larval food vs. adult food) varies with adult feeding ecology. The second hypothesis concerns the chemical identity of the two nutrient pools. This information allows us to understand the physiological mechanisms governing the relative use of larval and adult dietary nutrients in eggs. The third hypothesis explores how ecological factors, namely variation in nectar availability and time spent in flight, may affect allocation patterns within a species. Individuals of one species will be kept under varying conditions of food availability, and will be induced to fly for varying lengths of time daily. Stable carbon isotope composition of eggs from these individuals will be analyzed to yield understand how allocation to reproduction interacts with feeding conditions and flight expenditure. This experiment allows the extrapolation of our results to a field setting.The results of our proposed work will provide information on the relationships among nutritional ecology, energy metabolism, and reproduction. This information has particular practical value for butterflies and other insects, many species of which are threatened or are important indicators in conservation biology. More generally, however, the proposed research will provide an important conceptual and empirical foundation for further work on both nutrient dynamics and the evolution of life histories.