Drivers and consequences of individual specialization in an Arctic marine top predator

持续的气候变暖正在影响世界各地的生态系统。在北极，气候变暖的速度是地球其他地区的2-3倍，与冰有关的物种受到海冰面积和范围减少的严重影响。北极气候变暖的未来生态后果很难预测，至少部分原因是气候、栖息地和人口统计学之间的机械关系往往知之甚少。到目前为止，大多数生态学研究都认为动物种群是由生态上等价的个体组成的。然而，一项新出现的文献表明，个体专业化是生态过程和进化适应的重要驱动因素，即个体使用整个群体可用的资源的子集。我提出的研究涉及测试围绕环境驱动因素和个体专业化的生态后果的假设，使用北极熊(Ursus Maritimus)作为保护的模式物种和目标。作为动态栖息地的长寿顶级捕食者，北极熊表现出几个促进个体专业化的特征：种间竞争较低，种内竞争可能很强，个体觅食行为高度可变。作为一种依赖每年的海冰作为主要栖息地的物种，北极熊也很容易受到气候变暖导致的人口减少的影响。我实验室过去的研究发现，北极熊的饮食因地区、年龄和性别而异，觅食受到猎物可获得性和海冰条件的影响。我们已经开发并应用了一套测量身体状况和觅食成功的方法。使用跟踪食物成分从猎物到捕食者转移的生化方法，我们将估计在20年间采样的5000多只北极熊的食物组成。样本来自哈德逊湾的长期实地研究和努纳武特各地基于收获的采样，这两项努力自本世纪初以来一直在进行。关于熊的年龄、性别、身体大小和遗传相关性的数据将使我们能够测试关于饮食专业化的内在生物驱动因素的假设。我们将测试专业化如何影响营养状况和生殖成功，以及专业化模式是否会在社会上传播。我们将研究海冰条件和猎物可获得性的影响，并检验虎鲸(Orcinus Orca)迁徙到北极地区间接影响北极熊觅食的假设。我们将使用跟踪项圈来测试北极熊移动和使用它们栖息地的方式的专门化。通过确定影响北极顶级捕食者个体健康的因素，这项创新性的研究将促进动物生态学的进步，并为旨在保护北极熊的政策和行动提供参考，北极熊是加拿大具有重要文化和经济意义的物种。

Ongoing climate warming is affecting ecosystems worldwide. In the Arctic, where warming is occurring 2-3 times faster than the rest of the planet, ice-associated species have been acutely affected by declining sea ice area and extent. The future ecological consequences of Arctic climate warming are difficult to predict, at least partly because the mechanistic relationships between climate, habitat, and population demography are often poorly understood. To date, most ecological studies have considered animal populations as comprised of ecologically equivalent individuals. However, an emerging literature is demonstrating that individual specialization, whereby an individual uses a subset of resources available to the population as a whole, is an important driver of ecological processes and evolutionary adaptation. My proposed research involves testing hypotheses around the environmental drivers and ecological consequences of individual specialization, using the polar bear (Ursus maritimus) as a model species and target for conservation. As a long-lived top predator in a dynamic habitat, polar bears demonstrate several characteristics that promote individual specialization: interspecific competition is low, intraspecific competition may be strong, and individual foraging behaviour is highly variable. As a species that relies on the annual sea ice as its primary habitat, the polar bear is also vulnerable to demographic decline attributable to climatic warming. Past research from my lab has found that polar bear diets vary by region, age, and sex, and that foraging is affected by prey availability and sea ice conditions. We have developed and applied a suite of methods for measuring body condition and foraging success. Using biochemical methods that track the transfer of dietary components from prey to predators, we will estimate the diet composition of more than 5,000 polar bears sampled over a 20-year span. Samples come from long-term field studies in Hudson Bay and harvest-based sampling across Nunavut, both efforts ongoing since the early 2000s. Data on bear age, sex, body size, and genetic relatedness will allow us to test hypotheses about the intrinsic biological drivers of dietary specialization. We will test how specialization impacts nutritional condition and reproductive success and whether patterns of specialization are transmitted socially. We will examine the effects of sea ice conditions and prey availability and test the hypothesis that killer whales (Orcinus orca) migrating into the Arctic have indirectly affected polar bear foraging. We will use tracking collars to test for specialization in the way polar bears move and use their habitat. By identifying the factors contributing to individual fitness in an Arctic top predator, this innovative research will lead to advancement in animal ecology and inform policy and action aimed at the conservation of polar bears, a species of significant cultural and economic importance in Canada.