Unravelling population genetic structure of Arctogadus glacialis in Northeast Greenland with whole genome sequencing

Abstract

With rapidly increasing temperatures, reducing ice cover and lower albedo, the physico-chemical conditions in the Arctic fluctuate more than any other place on the planet, especially in the light of the current climate change. This has a severe effect on e.g. Arctic marine eco- systems, which make marine species good indicators, as they are in close contact with environmental gradients. One of which is the high-Arctic cryopelagic gadid Arctogadus glacialis (Peters, 1874), also known as ice cod. Due to its elusiveness, little is known about its biology, which is important knowledge to determine the implications of climate change. This project used a unique collection of A. glacialis from Northeast Greenland to investigate population genetic structure between and within fjord and shelf areas. Whole genome sequencing and population structure analyses of 110 individuals revealed overall population genetic structure between the two habitat types. Furthermore, the results revealed some genetic differentiation within fjord and shelf areas, respectively, but was inconsistent throughout the analyses, suggesting that population genetic software performed differently based on the data set. Based on the literature, this was the first study to investigate and detect population genetic structure in A. glacialis using whole genome sequencing. The structure between fjord and shelf areas was likely due to a post-glacial colonization of the fjords, where the individuals were later physically constrained as sill formation and sea level began to increase. Moreover, local adaptations to their respective environments, whether it was fjord or shelf, may also be associated to the observed population genetic structure. Future work is needed on the historical origin of A. glacialis and adaptive divergence, which would give implications of climate change’s effect on the species and the surrounding ecosystems.