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

博士论文研究：单性生殖昆虫对食物可利用性变化的生理和生活史反应。放大图片作者：Alison M.佛罗里达大学的生命史理论试图解释自然选择如何优化生命周期以最大限度地提高适应性。 这一理论体系的核心是预测，在当前和未来的繁殖、寿命和繁殖力、生长速度和寿命、卵的大小和窝卵数、成熟时的年龄和大小等性状之间会发生权衡。 这些权衡的存在意味着，生物体的能力是有限的，同时最大限度地增加获得的资源分配给影响适应性的各种特征。 虽然生活史文献中充满了在不同但恒定的食物供应水平下表现出的权衡的例子，但在动物的整个生命周期中，资源获取的变化是生活史实验中经常被忽视的组成部分。本研究的目的是评估如何限制和自由采食施加在不同阶段的动物的生命周期影响的生理和生活史特征的女性和他们的后代。 这项研究的新颖之处在于使用单性生殖物种（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，如配偶相容性，生长和发育速率的性别特异性差异，以及营养对卵子和精子产生的差异影响。 通过避免父系效应，单性生殖物种允许直接评估雌性中可变食物可用性对其后代的状况、生长和存活的影响。 由于这一物种在其一生中以相同的饮食（英国常春藤，常春藤螺旋）为食，因此可以在相同的食物来源上维持成虫和成虫，从而可以在不同阶段改变食物数量，而不会改变食物质量。 在这项研究中，生理和生活史的反应，以六种模式的可变的食物供应量施加在每个昆虫的一生将进行评估。 有了这些数据，生活史和分配模型（包括权衡的发生）的理论预测可以在不断变化的粮食供应条件下进行严格的测试。 此外，这项研究将深入了解不同发育阶段的食物供应差异对繁殖力和后代状况等对种群结构和动态有重大影响的响应变量的影响。 该项目通过来自不同背景的本科生的参与促进科学与教育的融合。 这些学生将有机会参加该项目的各个组成部分，成为志愿者或获得大学学分。 拟议研究的结果将通过展览、介绍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.