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. (2020). Documenting lemming population change in the Arctic: Can we detect trends? (Vol. 49).
Abstract: Lemmings are a key component of tundra food webs and changes in their dynamics can affect the whole ecosystem. We present a comprehensive overview of lemming monitoring and research activities, and assess recent trends in lemming abundance across the circumpolar Arctic. Since 2000, lemmings have been monitored at 49 sites of which 38 are still active. The sites were not evenly distributed with notably Russia and high Arctic Canada underrepresented. Abundance was monitored at all sites, but methods and levels of precision varied greatly. Other important attributes such as health, genetic diversity and potential drivers of population change, were often not monitored. There was no evidence that lemming populations were decreasing in general, although a negative trend was detected for low arctic populations sympatric with voles. To keep the pace of arctic change, we recommend maintaining long-term programmes while harmonizing methods, improving spatial coverage and integrating an ecosystem perspective.
Programme: 1036
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Duc Marine. (2020).
Abstract: Nb: Postponed Due To Covid Crisis
Programme: 1213
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Dupuis E., Sultan E. (2020).
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. (2020). Dome C coherence time statistics from DIMM data (Vol. 496).
Abstract: We present a reanalysis of several years of DIMM data at the site of Dome C, Antarctica, to provide measurements of the coherence time $\tau0$. Statistics and seasonal behaviour of $\tau0$ are given at two heights above the ground, 3m and 8m, for the wavelength $\lambda=500$nm. We found an annual median value of $2.9$ms at the height of 8m. A few measurements could also be obtained at the height of 20m and give a median value of 6ms during the period June--September. For the first time, we provide measurements of $\tau0$ in daytime during the summer, which appears to show the same time dependence as the seeing with a sharp maximum at 5pm local time. Exceptional values of $\tau0$ above 10ms are met at this particular moment. The continuous slow variations of turbulence conditions during the day offers a natural test bed for a solar adaptive optics system.
Keywords: Astrophysics – Instrumentation and Methods for Astrophysics
Programme: 1066
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E. Crubezy, O. Melnichuk, A. Alexeev. (2020). Bachelor's thesis, , .
Abstract: For the past 15 years, our research has focused on the evolution of the first Yakut populations, their interaction with local tribes as well as with the Russian population, which marks the beginning of Yakutia's development from the first half of the 17th century. We conducted the excavation of tombs and we analysed the cultural, historical and paleogenetic data uncovered. A review and a synthesis of the main results published in articles and monographs informs our research directions for the future.
Programme: 1038
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. (2020).
Keywords: cosmogenic nuclide dating deglaciation exhumation fission-track dating Late Palaeozoic Ice Age subglacial incision
Programme: 1003
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. (2020). Gravity Wave Excitation during the Coastal Transition of an Extreme Katabatic Flow in Antarctica (Vol. 77).
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. (2020). Behavioural adjustments during foraging in two diving seabirds: king and macaroni penguins (Vol. 167).
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. (2020). Circumpolar status of Arctic ptarmigan: Population dynamics and trends (Vol. 49).
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Eveline Pinseel, Steven B. Janssens, Elie Verleyen, Pieter Vanormelingen, Tyler J. Kohler, Elisabeth M. Biersma, Koen Sabbe, Bart Van de Vijver, Wim Vyverman. (2020). Global radiation in a rare biosphere soil diatom (Vol. 11). Bachelor's thesis, , .
Abstract: Soil micro-organisms drive the global carbon and nutrient cycles that underlie essential ecosystem functions. Yet, we are only beginning to grasp the drivers of terrestrial microbial diversity and biogeography, which presents a substantial barrier to understanding community dynamics and ecosystem functioning. This is especially true for soil protists, which despite their functional significance have received comparatively less interest than their bacterial counterparts. Here, we investigate the diversification of Pinnularia borealis, a rare biosphere soil diatom species complex, using a global sampling of >800 strains. We document unprecedented high levels of species-diversity, reflecting a global radiation since the Eocene/Oligocene global cooling. Our analyses suggest diversification was largely driven by colonization of novel geographic areas and subsequent evolution in isolation. These results illuminate our understanding of how protist diversity, biogeographical patterns, and members of the rare biosphere are generated, and suggest allopatric speciation to be a powerful mechanism for diversification of micro-organisms.
Keywords: Biogeography Phylogenetics Speciation
Programme: 136,1167
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