Monitoring Canada’s polar bear populations Anthropogenic activities are impacting species distributions and population sizes on an
unprecedented scale. This is especially true in the Arctic where human caused climate change is affecting many species and ecosystems. Monitoring polar bears can provide information on changes in not only the bear populations’ health but also on the over health of the Arctic ecosystem as they are the regions apex predator. The polar bear is also an important part of many cultural practices in northern communities making the preservation of this species a paramount issue in Arctic conservation. Polar bears are currently organized into 19 subpopulations for management. However, census estimates of these management units are infrequent due to the prohibitive costs and logistical challenges associated with traditional sampling methods. Recent research has also suggested the existence of 4 genetic clusters within Canada’s polar bear populations that might better represent the biological structure of this species. My research focuses on understanding the current genetic diversity of these clusters and the applications of new monitoring frameworks to management practices. Two key parameters that can help inform polar bear management are census population size (Nc) and effective population size (Ne). Census size is an estimate of the number of individual bears present within a management unit while effective population size is an estimate of genetic diversity present within polar bear populations. Both parameters are important when developing management plans as together they can describe the current and historic structure of a population. The ratio of Ne/Nc is also a common metric in conservation that is more easily compared between different populations of a given species and is often used when addressing quotas and hunting restrictions. Ultimately these parameters can lead to informed estimates of the long-term stability of a species. My research uses data from a new genotyping technique, Genotyping-in-Thousands by sequencing (GTseq), to generate a harvest tissue, fecal, and biopsy based estimates of Ne. The samples from which these estimates are derived are comprised of approximately 3200 bears collected from across the Canadian range of the species by our northern community collaborators with samples spanning 1997 to 2019. My research explores methods for estimating effective populations size (Ne) using temporal and single sample estimators from our GTseq data. This will not only allow us to demonstrate the current state of polar bear populations in Canada’s Arctic but also to gain insights into the future stability of this species. The effects of landscape on polar bear genetic structure The effects of climatic change and other anthropogenic stressors on Arctic wildlife can be studied using landscape genetics, or the integration of population genetic processes (i.e. gene flow, genetic drift) and landscape ecology. Landscape genetic studies have implicated changing habitat and climate as factors affecting population structure, and barriers or conduits to gene flow, including among continuously distributed species such as apex carnivores. Polar bears (Ursus martimus) exhibit contemporary genetic structure falling into diagnosable genetic groups, but also high genetic exchange, attributable to long distance movements and vast home ranges across both terrestrial and marine environments. Sea ice simultaneously facilitates movement and foraging for polar bears, and thus ice variability is predicted to affect distribution and population structure across spatial scales. My research examines the impacts of landscape (e.g. changing sea ice extents) on broad scale polar bear population genetic structure over time, focusing on populations across the Arctic Archipelago. Using decades of geographic and genomic data, I seek to quantify the relative influence of changing sea ice conditions on genetic structure in this region across time.
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