A new Genotyping-in-thousands by sequencing (GT-seq) panel for Canadian polar bears: population structure and sex-biased dispersal applications In the context of a rapidly warming arctic, effective management planning for polar bear (Ursus maritimus) subpopulations is limited by infrequent surveys and data deficits that preclude robust estimates of population trends. Genetic monitoring using non-invasively collected scat samples is an alternative that can mitigate some of the challenges associated with traditional monitoring (e.g. expensive, invasiveness) and provide opportunities for collaboration between Northern communities and Western scientists. Scat samples can provide numerous insights into individual- and population-level health, such as information on contaminants levels and diet. However, understanding this information relies on being able to reliably genetically identify individuals. To identify individual polar bears from non-invasive scat samples, we have developed and validated a new genomics method called Genotyping-in-Thousands by sequencing (GT-seq). We demonstrate that our new method can successfully genotype (>50% loci present) 62.9% and provide genetic identity for 80% of non-invasively collected fecal samples determined to contain polar bear DNA (i.e. from cells shed from the gut lining). Using an optimized, cost-efficient GT-seq panel of 324 Single Nucleotide Polymorphisms (SNPs), we are also able to comprehensively characterize polar bear population structure at similar levels to past studies that have used more invasive methods. Major contributors to contemporary population structure include dispersal (including sex-biased) and gene flow, yet few studies have been able to characterize sex-biased dispersal in Ursids. In my second data chapter, we aim to confirm sex-biased dispersal in polar bears using our new GT-seq assay and investigate density-dependent impacts on sex-biased dispersal through comparison of sex-biased dispersal patterns in subpopulations varying in bear density. This GT-seq test and the information it enables will provide the foundation of a non-invasive toolkit for polar bear monitoring and contribute to community-led programs - data from which can inform co-existence with polar bears, conservation, and policy decisions.
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