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提供这些限制的因素。虽然人口调控是明确的人口普查的众多人口随着时间的推移，实际机制负责的监管不太明显，也许是由于缺乏大规模的实地实验。 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易处理性，也是因为它们对加拿大人经济和文化生活的重要性。长期观测研究表明，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不依赖于密度。我们以前的工作已经描述了如何在流中的个别青少年的领土大小的变化，以应对关键的环境因素。特别是，我们发现，领土大小随着人口密度的增加而逐渐减小到渐近最小值，这可能是一个流可以产生的个体数量的最终限制。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。 在这个建议中，我们采取实地，实验的方法来解决差距在我们的理解之间的行为生态学的个人和鲑鱼种群的动态。在一系列的现场实验中，我们将确定的三个主要机制的相对重要性流鲑：密度依赖性死亡率，移民/扩散，和个人的增长率。我们将操纵的密度和大小结构的年轻溪鳟在小部分的流描述的人口动态和推断的竞争机制，在复制流在开普种族，纽芬兰。在与渔业生物学家与美国鱼类和野生动物管理局的合作中，我们将操纵在尚普兰湖流域的多个溪流中放养的年轻大西洋鲑鱼的数量，以确定负责扩散的行为机制，以及扩散是否依赖于密度。在我们在新玩法的长期实地考察中，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鱼密度的可行的长期方法。 这一建议将提供一个模型脊椎动物系统的种群动力学的基本见解。我们的研究结果也将对如何管理、收获和恢复这些宝贵的鱼类种群产生实际影响。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.