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

持续的气候变暖正在影响全球的生态系统。在北极，变暖的速度比地球上其他地方快2-3倍，与冰有关的物种受到海冰面积和范围下降的严重影响。北极气候变暖的未来生态后果很难预测，至少部分原因是人们对气候、栖息地和人口统计之间的机制关系往往知之甚少。迄今为止，大多数生态学研究都认为动物种群是由生态相等的个体组成的。然而，一个新兴的文献表明，个体专业化，即个体使用整个群体可用的资源子集，是生态过程和进化适应的重要驱动力。我提议的研究包括测试关于个体专业化的环境驱动因素和生态后果的假设，使用北极熊（Ursus maritimus）作为模型物种和保护目标。作为一种生活在动态栖息地的长寿的顶级捕食者，北极熊表现出几个促进个体专业化的特征：种间竞争低，种内竞争可能很强，个体觅食行为高度可变。作为一个以每年的海冰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。我的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，觅食受到猎物可用性和海冰状况的影响。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。利用追踪食物成分从猎物到捕食者的转移的生化方法，我们将估计在20年的时间里取样的5000多只北极熊的饮食组成。样本来自哈德逊湾的长期实地研究和努纳武特地区的收获取样，这两项工作自21世纪初以来一直在进行。关于熊的年龄、性别、体型和遗传关系的数据将使我们能够检验关于饮食专业化的内在生物学驱动因素的假设。我们将测试专业化如何影响营养状况和繁殖成功，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用性的影响，并验证虎鲸（Orcinus orca）迁移到北极间接影响北极熊觅食的假设。我们将使用追踪项圈来测试北极熊移动和使用栖息地的方式是否专业化。通过确定影响北极顶级掠食者个体健康的因素，这项创新研究将导致动物生态学的进步，并为旨在保护北极熊的政策和行动提供信息，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.