Dissertation Research: Physiological and life-history responses to variation in food availability in a parthenogenetic insect

论文研究：单性生殖昆虫对食物供应变化的生理和生活史反应佛罗里达大学生活史理论试图解释自然选择如何优化生命周期以最大化适应性。这一理论体系的核心是预测当前和未来的繁殖、寿命和繁殖力、生长速度和寿命、卵的大小和窝的大小、成熟时的年龄和大小等特征之间会发生权衡。这些权衡的存在意味着生物体同时最大化分配给影响适应性的各种性状的获得资源的能力是有限的。尽管生命史文献中充满了在不同但恒定的食物供应水平下表现出权衡的例子，但在动物的整个生命周期中，资源获取的变化往往是生命史实验中被忽视的一个组成部分。本研究的目的是评估在动物生命周期的不同阶段施加限制和自由摄食对雌性及其后代的生理和生活史性状的影响。这项研究的新颖之处在于使用一种孤雌生殖物种（印度竹节虫，Carausius morosus）作为动物模型。这种方法避免了圈养交配的需要，从而避免了潜在的复杂因素，如配偶兼容性、生长和发育速度的性别差异以及营养对卵子和精子产生的不同影响。通过避免父亲的影响，孤雌生殖物种可以直接评估雌性可变食物供应对其后代的状况、生长和生存的影响。由于该物种一生都以相同的食物（英国常春藤，Hedera helix）为食，若虫和成虫可以保持在相同的食物来源上，因此在不同的阶段，食物的数量可以改变，而食物的质量也不会改变。在整个研究中，将评估每种昆虫一生中对六种可变食物供应模式的生理和生活史反应。有了这些数据，生活史和分配模型的理论预测（包括权衡的发生）可以在不断变化的食物供应条件下进行严格的测试。此外，本研究将深入了解不同发育阶段食物供应差异对繁殖力和后代状况等响应变量的影响，这些变量对种群结构和动态有重大影响。该项目通过不同背景的本科生的参与促进科学与教育的融合。这些学生将有机会成为志愿者或通过参与项目的各个组成部分获得大学学分。拟议研究的结果将通过展览、演讲和出版物向广大受众传播。这项研究将深入了解摄入模式对健康的影响，因此将引起科学家和公众的兴趣。

Dissertation Research: Physiological and life-history responses to variation in food availability in a parthenogenetic insectKaren A. Bjorndal and Alison M. RoarkUniversity of Florida Life-history theory seeks to explain how natural selection has optimized life cycles to maximize fitness. Central to this body of theory is the prediction that trade-offs occur between traits such as current and future reproduction, longevity and fecundity, growth rate and longevity, egg size and clutch size, and age and size at maturity. The existence of these trade-offs implies that organisms are limited in their capacity to maximize simultaneously the amount of acquired resources allocated to various traits that influence fitness. Although life-history literature is replete with examples of trade-offs exhibited under different but constant levels of food availability, variation in resource acquisition throughout an animal's lifespan is an often overlooked component of life-history experimentation. The purpose of this study is to evaluate how restricted and ad libitum feeding imposed at different stages of an animal's life cycle affect physiological and life-history traits of females and their offspring. The novelty of this study is the use of a parthenogenetic species (the Indian stick insect, Carausius morosus) as the animal model. This approach obviates the need for captive mating and thus avoids potential complicating factors such as mate compatibility, gender-specific differences in growth and development rates, and differential effects of nutrition on egg and sperm production. By avoiding paternal effects, a parthenogenetic species allows direct evaluation of the effects of variable food availability in females on the condition, growth, and survival of their offspring. Because this species feeds on the same diet (English ivy, Hedera helix) throughout its lifetime, nymphs and adults can be maintained on the same food source so that food quantity can be varied at different stages without also varying food quality. Throughout this study, physiological and life-history responses to six patterns of variable food availability imposed throughout each insect's lifetime will be evaluated. With these data, the theoretical predictions of life-history and allocation models (including the occurrence of trade-offs) can be rigorously tested under conditions of changing food availability. Furthermore, this study will yield insights into the effects of differences in food availability at different developmental stages on response variables such as fecundity and offspring condition that have substantial influences on population structure and dynamics. This project promotes integration of science and education through the participation of undergraduate students from diverse backgrounds. These students will have the opportunity to volunteer or to obtain college credits for their involvement in various components of the project. The results of the proposed study will be disseminated to a broad audience via displays, presentations, and publications. This research will yield insights into the effects of intake pattern on fitness and will therefore be of interest to scientists and the general public.