Facultative Feeding by Planktotrophic Larvae of Echinoids

海胆浮游营养幼虫的兼性摄食

• 批准号: 9819593
• 负责人: David Julian
• 金额: --
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-03-01 至 2003-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9819593&HistoricalAwards=false
• 关键词: Facultative; Feeding; Planktotrophic; Larvae; Echinoids

McEdward Advances in our understanding of the ecology of reproduction and development in marine organisms require combining life history theory with functional analyses of larvae as pelagic organisms. This combination should prove to be an important integrative link between these fields . A central question will be what ecological factors influence the development of feeding larvae? A concentration on energetics is important because this is central to many general theoretical models of life history ecology and evolution. This project will provide new information on the development of planktotrophic larvae by evaluating the consequences of facultative feeding in a closely related, co-occurring group of echinoids that differ widely in egg size. Traditionally marine invertebrate larvae have been classified into two mutually exclusive, qualitatively different nutritional types: feeding and non-feeding. Most larvae that require food for development are thought to come from very small eggs and require food throughout larval life. Non-feeding larvae develop from very large yolky eggs and cannot obtain or utilize exogenous food until after metamorphosis. Many life history traits are correlated with nutritional mode, such as egg size, fecundity, larval morphology, development time, and juvenile size. Empirical observations of the distribution of life history traits and theoretical modeling of larval strategies have led to the view that the extremes of the two nutritional patterns represent the most successful reproductive strategies. Recent work on the feeding requirements of echinoid larvae challenges the predictions made by the classic models of reproductive strategies in marine invertebrates. A surprising range of "intermediate" strategies that had not been recognized before, nor predicted, has been documented. Among echinoids (sea urchins and sand dollars) there exists a continuum of feeding strategies across which larvae vary substantially in the degree to which they require food for development to metamorphosis. The amount of nutritional reserves provided in the egg by the parent is positively correlated with the stage at which the larvae require exogenous food. It is predicted that egg energy content also determines the capacity for facultative feeding, i.e., the ability to acquire exogenous food before endogenous reserves are exhausted and feeding becomes obligatory. The lack of information on facultative larval feeding precludes a meaningful assessment of the ecological and evolutionary implications of differences in larval strategies. The project seeks to assess the contribution of facultative feeding in planktotrophic echinoid larvae. Two approaches will be used. First, laboratory experiments will be used to evaluate empirically the contribution of facultative feeding to larval development rate and juvenile energy content in six related, co-occurring species that have different egg sizes and different abilities to develop in the absence of food. Second, new theoretical models of larval development and growth will be constructed to analyze the consequences of facultative feeding on the relative advantages of different levels of parental investment. These studies are designed to generate new information on the relationships that underlie the diversity of larval strategies among marine invertebrates.

麦克爱德华在理解海洋生物繁殖和发育的生态学方面取得进展，需要将生活史理论与对作为远洋生物的幼虫的功能分析结合起来。这一结合应该被证明是这些领域之间的重要综合纽带。一个中心问题将是什么生态因素影响摄食性幼虫的发育？专注于能量学是重要的，因为这是生命、历史、生态和进化的许多一般理论模型的核心。该项目将通过评估在蛋大小差异很大的密切相关、共同出现的棘球类群体中兼性摄食的后果，提供关于浮游营养型幼虫发育的新信息。传统上，海洋无脊椎动物幼虫被分为两种互不相容、性质不同的营养类型：摄食和不摄食。大多数需要食物才能发育的幼虫被认为来自非常小的卵，需要整个幼虫一生的食物。不取食的幼虫从非常大的蛋黄卵发育而来，直到变态后才能获得或利用外源食物。许多生活史性状与营养方式有关，如卵大小、繁殖力、幼虫形态、发育时间和幼虫大小。对幼虫生活史特征分布的经验观察和幼虫策略的理论建模导致了这样的观点，即这两种营养模式的极端代表了最成功的繁殖策略。最近关于棘球藻类幼虫摄食需求的研究挑战了海洋无脊椎动物生殖策略的经典模型所做的预测。令人惊讶的是，有一系列以前没有被认识到，也没有预测到的“中间”战略已经被记录在案。在棘球类动物(海胆和沙鱼)中，存在着一系列的摄食策略，幼虫在发育到变态所需食物的程度上有很大的不同。父母在卵中提供的营养储备量与幼虫需要外源食物的阶段呈正相关。据预测，鸡蛋的能量含量也决定了兼性摄食的能力，即在内源储备耗尽和摄食变得强制性之前获得外源食物的能力。缺乏有关兼性幼虫摄食的信息，妨碍了对幼虫策略差异的生态和进化影响进行有意义的评估。该项目旨在评估兼性摄食对浮游营养型棘棘类幼虫的贡献。将使用两种方法。首先，将通过实验室实验来经验地评估兼性摄食对六个相关的共生物种的幼虫发育率和幼体能量含量的贡献，这些物种具有不同的卵大小和在没有食物的情况下发育的不同能力。其次，将构建新的幼虫发育和生长理论模型，分析兼性饲养对不同水平亲本投入的相对优势的影响。这些研究旨在产生关于海洋无脊椎动物幼虫策略多样性所依据的关系的新信息。