Interference competition: consequences for individuals and populations

野生种群的大小随时间而波动，但通常在上限和下限之间。种群生态学的一个基本目标是确定造成这些限制的因素。虽然从长期的大量人口普查中可以清楚地看出人口调节，但负责调节的实际机制却不太明显，这可能是由于缺乏大规模的实地实验。******溪流中的鲑鱼种群已经成为研究种群动态的重要模型系统，这既是因为它们作为实验系统的可追溯性，也是因为它们对加拿大人的经济和文化生活的重要性。长期观察研究表明，淡水环境中的种群调节依赖于密度，而海洋环境中的种群调节与密度无关。我们之前的工作描述了溪流中个体幼鱼的领土大小如何随关键环境因素而变化。特别是，我们发现领土大小随着种群密度的增加而逐渐减小到一个渐进的最小值，这可能为溪流可以产生的个体数量提供最终限制。然而，缺乏实验证据将个体水平上发生的事情与群体水平上的动态联系起来。******在本提案中，我们采取实地实验方法来解决我们对个体行为生态学和鲑鱼种群动态之间理解的差距。在一系列的野外实验中，我们将确定河流鲑鱼种群调节的三种主要机制的相对重要性：密度依赖性死亡率、迁移/扩散和个体生长率。我们将在纽芬兰开普Race的小段溪流中操纵小鳟鱼的密度和大小结构，以描述种群动态并推断复制溪流中的竞争机制。与美国鱼类和野生动物管理局的渔业生物学家合作，我们将控制尚普兰湖流域多个河流中储存的大西洋鲑鱼幼鱼的数量，以确定负责扩散的行为机制，以及扩散是否依赖于密度。在我们位于新不伦瑞克省的长期现场，我们将测试在溪流中添加巨石是否是恢复栖息地复杂性和增加溪流中大西洋鲑鱼幼崽密度的可行长期方法。******这一建议将为模型脊椎动物系统的种群动态提供基本的见解。我们的研究结果也将对如何管理、捕捞和恢复这些宝贵的鱼类种群具有实际意义。我的学生将接受纯生态学和应用生态学的培训，使他们能够从事学术、渔业生物学和保护科学方面的职业。

Wild populations fluctuate in size over time, but typically between upper and lower limits. A fundamental goal of population ecology is to determine the factors that provide these limits. While population regulation is clear from the census of numerous populations over time, the actual mechanisms responsible for the regulation are less obvious, perhaps due to a paucity of large-scale field experiments. ******Salmonid populations in streams have emerged as important model systems for studying population dynamics, both for their tractability as experimental systems, and their importance to the economic and cultural lives of Canadians. Long-term observational studies suggest density-dependent population regulation in freshwater environments and density-independent regulation in marine environments. Our previous work has described how the territory size of individual juveniles in streams change in response to key environmental factors. In particular, we showed that territory size decreases towards an asymptotic minimum size with increasing population density, potentially providing the ultimate limit to the number of individuals that a stream can produce. However, there is a lack of experimental evidence to link what happens at the individual level to the dynamics at a population level. ******In this proposal, we take a field, experimental approach to address the gap in our understanding between the behavioural ecology of individuals and the dynamics of salmonid populations. In a series of field experiments, we will determine the relative importance of the three primary mechanisms of population regulation in stream salmonids: density-dependent mortality, emigration/dispersal, and individual growth rate. We will manipulate the density and size structure of young brook trout in small sections of streams to describe the population dynamics and infer the mechanisms of competition in replicate streams in Cape Race, Newfoundland. In collaboration with fisheries biologists with the U.S. Fish & Wildlife Service, we will manipulate the number of young Atlantic salmon that are stocked into multiple stream reaches in a Lake Champlain watershed to determine the behavioural mechanisms responsible for dispersal, and whether dispersal is density dependent or not. At our long-term field sites in New Brunswick, we will test whether adding boulders to streams is a viable long-term method for restoring habitat complexity and increasing the density of juvenile Atlantic salmon in streams. ******This proposal will provide fundamental insight into the population dynamics of a model vertebrate system. Our results will also have practical implications for how to manage, harvest and restore these valuable fish populations. My students will receive training in pure and applied ecology, allowing them to pursue careers in academics, fisheries biology and conservation science.