Life history adaptations of larvacean tunicates to environmental variability

我的长期目标是确定冷海洋浮游动物对环境条件的整体适应。这一点很重要，因为适应性决定了关键的生活史特征，如成熟时的年龄和大小、繁殖力（即产蛋率）和死亡率，它们共同决定了季节性和年际的补充和丰度周期。生活史性状受到强烈的选择压力和快速的进化变化。我的指导概念模型是来自进化理论的经典生命史优化模型，其中关键特征受到生理权衡的影响，许多与身体大小有关。例如，生活史理论预测，身体尺寸的增加会导致繁殖力的增加，从而增加终身健康。然而，如果增加的体型需要增加的发育时间，导致被吃掉的可能性增加，那么增加的繁殖力可能会被权衡所阻止。 在这一建议中，我概述了未来五年的两个目标：（1）确定冷海洋幼虫类被囊动物的生殖分配和繁殖力，（2）确定其最佳年龄和成熟时的大小。生殖分配将以各种方式确定，包括投资于鸡蛋的脂质和脂肪酸的数量。一种假设是，幼虫是非常熟练的离合器大小的操纵者，由于一种新的机制，选择成熟的鸡蛋在生命周期的很晚，以应对食物质量。这是如何发生的尚不清楚。在第二个目标，我将确定最佳的年龄和大小，在成熟的幼虫，并测试预测从经典的优化理论和一个新的，基于温度的机械模型。从本质上讲，我将回答幼虫类动物是以固定的大小繁殖，还是以固定的年龄繁殖的问题。这项研究将有助于推动对海洋浮游动物的研究超越过去的生物地球化学方法，并进入生活史理论背景。这将有利于学术和政府部门的海洋科学家、政府监管机构以及渔业和水产养殖业。

My long term goal is to determine whole-organism adaptations of cold ocean zooplankton to environmental conditions. This is important because adaptations determine key life history traits, such as age and size-at-maturity, fecundity (i.e. egg production rate), and mortality, which together determine seasonal and interannual cycles of recruitment and abundance. Life history traits are subject to intense selection pressure and rapid evolutionary change. My guiding conceptual model is the classical life history optimization model from evolutionary theory, in which key traits are subject to physiological trade-offs, many related to body size. For example, life history theory predicts that increased body size results in increased fecundity and thus increased lifetime fitness. However, increased fecundity may be prevented by trade-offs if increased body size requires increased development time resulting in increased probability of being eaten. In this proposal I outline two objectives for the next five years; (1) to determine the reproductive allocation and fecundity of cold ocean larvacean tunicates, and (2) to determine their optimal age and size-at-maturity. Reproductive allocation will be determined in various ways, including the quantity of lipids and fatty acids invested in eggs. One hypothesis is that larvaceans are highly adept clutch size manipulators, due to a novel mechanism of selection of eggs for maturation very late in the life cycle in response to food quality. How this occurs is not known. In the second objective, I will determine the optimal age and size-at-maturity of larvaceans, and test predictions from classical optimization theory and a new, temperature-based mechanistic model. In essence, I will answer the question of whether larvaceans reproduce at a fixed size, or at a fixed age. This research will contribute to moving research on marine zooplankton beyond the biogeochemical approach of the past and into a life history theoretical context. It will be of benefit to marine scientists in both the academic and government sectors, government regulators and fisheries and aquaculture.