Conservation Genomics of the Long-tailed Duck

Abstract: With increasingly warming climate, many bird species have been forced to respond to environmental changes, and the long-tailed duck (Clangula hyemalis) is no exception. The populations of the long-tailed duck have been in decline the past few decades and the species is classified as globally vulnerable and near threatened in both Iceland and Sweden. The long-tailed duck is a circumpolar, migratory sea duck. Its migratory routes and wintering and breeding sites might play an important part in gene flow between populations. The aim of this project was to get a clearer image of the substructure of the long-tailed duck in the northern hemisphere to help identify populations possibly at risk. This was investigated by exploring differences in mitochondrial DNA between the global populations, and by studying the Icelandic wintering and breeding populations in particular applying whole genome sequencing. To do this, samples were obtained for mitochondrial DNA analyses from a previous study by Wilson et al. (2016) from North America and East Russia, samples from other populations around the northern hemisphere as well and new samples from Iceland. Museum samples from Iceland were used for whole genome resequencing. Mitochondrial analyses included haplotype identification, population comparisons, mismatch and neutrality tests. Whole genome analyses included neutrality tests, principal component analysis and genetic admixture analysis.The mitochondrial results revealed two distinct lineages for the long-tailed duck. Two populations showed a difference from the other populations; the Icelandic breeding population and the Yukon-Kuskokwim Delta population from Alaska, which are the southernmost breeding populations. The Yukon population might have been previously isolated with refugial population intermixing. For the Icelandic populations, the mitochondrial results showed little intermixing between the winter and breeding populations. The whole genome results showed more complicated results for the Icelandic populations, with admixture in some individuals. This suggests that there seems to be more variation in the genome than implied by the mitochondrial DNA.