Does mating success determine population growth rate at low abundance in marine copepods?

在有性繁殖的生物体中，成功的交配是种群增长的先决条件。与人口增长的其他决定因素不同，交配成功率与人口密度呈负相关，从而导致增长率与当地人口密度之间的负密度依赖关系。由此产生的反馈应防止稀释种群持续存在或增长；然而，它们确实存在。本项目将研究低密度下交配成功率低对抑制桡足类种群增长率的潜在影响。这项研究将建立在先前的桡足类交配研究的基础上，这些研究强调行为和生理；然而，这项研究的重点将放在行为的后果上。也就是说，一系列的实验将支持一个模型，即成功交配的概率是当地成年种群密度的函数。来自河口环境的桡足类动物将被使用，因为它们可能适应高密度，因此最有可能在低密度下显示效果。交配成功概率模型描述了相遇率，就像描述喂食的模型一样（Gerritsen 1980），以及简化的种群动态。尽管行为研究已经确定了交配的体积搜索率，但实际交配的条件概率尚未确定。模型参数包括体积搜索率与该条件概率的乘积；该产品，而不是其成分，将根据实验结果确定。实验工作将研究在密度、性别比例、容器大小和食物浓度等不同条件下，被关在一起的未交配桡足类的交配频率。这些实验将使用具有一系列游泳和搜索行为的各种桡足类来进行，试图确定这些行为如何导致不同的交配频率。初步和辅助实验将测试实验人工制品和问题，如雄性交配后再生精子的时间。桡足动物性比是交配概率的关键参数，环境决定因素也将被研究，重点是饮食脂肪的潜在作用。智力优势：浮游动物在海洋食物网中占有关键地位，它们的种群动态一直是大量研究的主题。在种群增长率的决定因素中，交配成功率的研究相对较少，而且大多数研究都集中在行为和解剖结构上。然而，交配成功应该是种群从低丰度时期恢复以及从初始种子建立新种群的关键决定因素。这项研究建立在以前的工作基础上，包括了交配的所有组成部分（Buskey 1998），而不仅仅是相遇率。更广泛的影响：这项研究的结果将在两个对社会重要的领域产生影响。首先，入侵物种，沿海水域的一个主要问题，必须从最初的小接种建立种群，因此受到这里讨论的正反馈。其次，这些结果至少在原则上可以转移到其他分类类群的濒危和稀有物种的研究中。拟议中的研究还将为在旧金山州立大学（San Francisco State University）撰写硕士论文提供机会，从而为教育做出贡献。旧金山州立大学是一所为少数族裔服务的机构。

Successful mating is a prerequisite for population growth in organisms that reproduce sexually. Unlike other determinants of population growth, mating success is inversely related to population density, resulting in an inverse density-dependent relationship between rate of increase and local population density. The resulting feedback should prevent dilute populations from persisting or growing; yet, they do persist. This project will examine the potential for poor mating success to suppress rate of increase of copepod populations at low density. This study will build on previous studies of mating in copepods that emphasized behavior and physiology; however, the focus of this research will be on consequences of behavior. That is, a series of experiments will support a model of the probability of successful mating as a function of local population density of adults. Copepods from an estuarine environment will be used under the expectation that they may be adapted to high density and therefore most likely to show effects at low density. The mating success probability model describes encounter rate, as in models describing feeding (Gerritsen 1980), together with simplified population dynamics. Although behavioral studies have determined volume search rates for mating, the conditional probability of actually mating upon encounter has not been determined. Model parameters include the product of the volume search rate and this conditional probability; this product, rather than its components, will be determined from experimental results. The experimental work will examine the frequency of mating in unmated copepods confined together under various conditions of density, sex ratio, container size, and food concentration. These experiments will be conducted using copepods of various species with a range of swimming and searching behaviors in an attempt to determine how these behaviors result in different mating frequencies. Preliminary and ancillary experiments will test for experimental artifacts and issues such as time for males to regenerate sperm after mating. Environmental determinants of copepod sex ratio, a key parameter in mating probability, will also be examined with an emphasis on the potential role of dietary lipids. Intellectual merit: Zooplankton occupy a key role in oceanic foodwebs, and their population dynamics has been the subject of considerable research. Among determinants of population growth rate, mating success has received relatively little study, and most of that has been on behavior and anatomical structure. Yet, mating success should be a key determinant of recovery of populations from periods of low abundance, as well as establishment of new populations from initial seeds. This research builds on previous work to include all components of mating (Buskey 1998) rather than only encounter rate. Broader impacts: The results of this research will have impacts in two areas important to society. First, invasive species, a major concern in coastal waters, must establish populations from initially small inocula, which are therefore subject to the positive feedback addressed here. Second, these results may be transferable, at least in principle, to the study of endangered and rare species of other taxonomic groups. The proposed research will also contribute to education by providing an opportunity for a Master's thesis at San Francisco State University, a minority-serving institution.