The evolution of life histories in geminate echinoderms: a comparative approach to unscrambling the relationships among environment, egg size, and the energetics of development.

卵大小是海洋生物生活史上最重要和研究最多的方面之一，与幼体发育方式、幼体发育历时、抗饥性、幼体形态和功能、变态大小、幼体生长和存活等诸多特征有关。许多注意力集中在驱动卵大小进化变化的生态因素上，但幼虫发育的生态、进化和生理方面之间的关系尚未确定。同样，虽然关于卵大小和发育中的幼虫利用卵能量之间的关系的假设被纳入海洋生物生活史进化的所有主要模型，但还没有研究在严格的比较框架内与描述良好的生态和进化背景下明确地测试这些模型的基本假设。为了检验这些假设，首席调查员将使用因中美洲航道关闭而分离的棘皮动物成对双生物种作为一个模型系统，以了解卵大小的演变及其对海洋无脊椎动物中广泛的其他生活史相关的影响。这项研究要解决的具体问题包括：(1)与蛋大小进化变化相关的生化组成的变化是什么？(2)蛋大小、蛋组成和总能量的进化差异如何影响幼虫的生长速度和发育轨迹？(3)在浮游营养型物种中，较大的蛋是否比较小的蛋在总发育成本中贡献了更高的能量比例？(4)在模仿两大洋不同自然食物环境的不同食物制度下，蛋大小如何影响后续幼虫的表现？更广泛的影响包括资助一名博士后研究员、两名研究生和至少三名本科生。学生将直接参与在巴拿马收集的样本的工作，并将通过直接(在教师的监督下)使用他们自己收集的数据集来学习比较生物学、数据获取和组织以及数据分析的原理。这项研究将通过克莱姆森大学托管的网页向公众传达，并由首席调查员维护，并将作为开发“幼虫维基”的基础，这是一种可供任何人投稿和编辑的公共网络资源。首席研究人员希望这个维基将成为一个自给自足的资源，对全球幼虫生物学家社区有相当大的用处，作为讨论重大问题、传播信息和分享照片以供教学和公开演示的论坛。

Egg size is one of the most important and often-studied aspects of the life history of marine organisms, and is correlated with many traits including larval developmental mode, length of larval development, starvation resistance, larval form and function, size at metamorphosis, and juvenile growth and survival. Much attention has focused on the ecological factors that drive evolutionary changes in egg size, but the relationships between ecological, evolutionary, and physiological aspects of larval development have yet to be characterized. Likewise, while assumptions about the relationships between egg size and the utilization of egg energy by developing larvae are built into all major models of life history evolution in marine organisms, no study has explicitly tested the underlying assumptions of these models in a rigorous comparative framework with a well-described ecological and evolutionary context. To examine these assumptions, the principle investigator will use geminate species pairs of echinoderms separated by the closure of the Central American Seaway as a model system for understanding the evolution of egg size and its implications for a wide range of other life history correlates among marine invertebrates. Specific questions to address by the research include: (1) What are the changes in biochemical composition that are associated with evolutionary changes in egg size? (2) How do evolved differences in egg size, egg composition, and total egg energy affect the growth rates and developmental trajectories of larvae? (3) In planktotrophic species, do larger eggs contribute a higher proportion of energy to the total cost of development than smaller eggs? (4) How does egg size affect subsequent larval performance under different food regimes that mimic the contrasting natural food environments in the two oceans? The broader impacts include funding one postdoctoral researcher, two graduate students, and at least 3 undergraduates. Students will be directly involved working with samples collected in Panama, and will learn the principles of comparative biology, data acquisition and organization, and data analysis by working directly (under faculty supervision) with datasets they collect themselves. This research will be communicated to the public via a web page hosted at Clemson University and maintained by the principle investigator and will serve as the foundation for the development of a "Larval Wiki," a public web resource that can be contributed to and edited by anyone. The principle investigator hopes this Wiki will become a self-sustaining resource that will be of considerable use to the global community of larval biologists as a forum for discussing major issues, disseminating information, and sharing photographs for teaching and public presentations.