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Vincent Zvénigorosky, Sylvie Duchesne, Liubomira Romanova, Patrice Gérard, Christiane Petit, Michel Petit, Anatoly Alexeev, Olga Melnichuk, Angéla Gonzalez, Jean-Luc Fausser, Aisen Solovyev, Georgii Romanov, Nikolay Barashkov, Sardana Fedorova, Bertrand Ludes, Eric Crubézy, Christine Keyser. (2020). The genetic legacy of legendary and historical Siberian chieftains (Vol. 3). Bachelor's thesis, , .
Abstract: Seventeen years of archaeological and anthropological expeditions in North-Eastern Siberia (in the Sakha Republic, Yakutia) have permitted the genetic analysis of 150 ancient (15th-19th century) and 510 modern individuals. Almost all males were successfully analysed (Y-STR) and this allowed us to identify paternal lineages and their geographical expansion through time. This genetic data was confronted with mythological, historical and material evidence to establish the sequence of events that built the modern Yakut genetic diversity. We show that the ancient Yakuts recovered from this large collection of graves are not representative of an ancient population. Uncommonly, we were also able to demonstrate that the funerary preference observed here involved three specific male lineages, especially in the 18th century. Moreover, this dominance was likely caused by the Russian conquest of Siberia which allowed some male clans to rise to new levels of power. Finally, we give indications that some mythical and historical figures might have been the actors of those genetic changes. These results help us reconsider the genetic dynamics of colonization in some regions, question the distinction between fact and myth in national histories and provide a rare insight into a funerary ensemble by revealing the biased process of its composition.
Programme: 1038
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Chuxian Li, Jeroen E. Sonke, Gaël Le Roux, Natalia Piotrowska, Nathalie Van der Putten, Stephen J. Roberts, Tim Daley, Emma Rice, Roland Gehrels, Maxime Enrico, Dmitri Mauquoy, Thomas P. Roland, François De Vleeschouwer. (2020). Unequal Anthropogenic Enrichment of Mercury in Earth’s Northern and Southern Hemispheres (Vol. 4). Bachelor's thesis, , .
Abstract: Remote Northern Hemisphere (NH) and Southern Hemisphere (SH) lake sediment and peat records of mercury (Hg) deposition have shown a ×3 to ×5 Hg enrichment since pre-industrial times (<1880 AD), leading to the perception that global atmospheric Hg enrichment is moderate and uniform across the hemispheres. Anthropogenic Hg emissions in the NH are, however, approximately 4 times higher than those in the SH. Here, we reconstruct atmospheric Hg deposition in four remote SH peatlands and review sediment and peat Hg records from both hemispheres. We observe a ×4 all-time enrichment in SH Hg deposition from pre-anthropogenic (<1450 AD) to the late 20th-century periods, which is lower than the large ×16 all-time enrichment in NH Hg deposition. We attribute this difference to lower anthropogenic Hg emissions in the SH, and higher natural atmospheric SH Hg concentrations, supported by ×2 higher natural background Hg accumulation in SH peat records. We suggest that the higher SH natural atmospheric Hg deposition reflects the SH land–ocean distribution, and is driven by important SH marine Hg emissions. Our findings indicate that atmospheric Hg background levels and anthropogenic enrichment in both hemispheres are different and should be taken into account in international Hg assessments and environmental policy.
Programme: 1065,1133
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Lorène Julia Marchand, Michèle Tarayre, Thomas Dorey, Yann Rantier, Françoise Hennion. (2020). Morphological variability of cushion plant Lyallia kerguelensis (Caryophyllales) in relation to environmental conditions and geography in the Kerguelen Islands: implications for cushion necrosis and climate change (Vol. 44). Bachelor's thesis, , .
Abstract: In recent decades, climate change has been faster in various parts of the world. Within species, to counter rapid climate changes shift of geographical area, individuals’ plastic responses or populations’ genetic adaptation might occur. The sub-Antarctic islands are subject to one of the most rapid climate changes on earth, with already visible impacts on native vegetation. Such might be the case of Lyallia kerguelensis a cushion plant strictly endemic to the Kerguelen Islands. In L. kerguelensis, necrotic parts were observed in cushions these last decades and possibly related to water stress. We analysed morphological variability of L. kerguelensis, including necrosis extent, across 19 populations spanning a wide range of environments across the Kerguelen Islands. Inter-population variations in the cushion surface area, shape and compactness were well explained by topography, degree of wind exposure, slope aspect, proportions of coarse sand and bare soil, and geographical distance between populations. All these variables are related to wind intensity and water availability. Moreover, in cushions with less than 10% necrosis in surface area, necrosis extent was positively correlated to soil sodium. Sodium availability might reduce the plant’s capacity for osmotic adjustment in face of other abiotic stresses, such as water stress. We conclude that cushion morphology may have the capacity to adjust to environmental variation, including aspects of climate change, but that cushion necrosis may be accelerated in the driest and most saline environments.
Programme: 1116
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Amandine Gamble, Henri Weimerskirch, Thierry Boulinier. (2020). Seabirds blinded by ticks (Vol. 18). Bachelor's thesis, , .
Abstract: In December 2017, on Possession Island (part of the Crozet Archipelago in the southern Indian Ocean), we observed two breeding white‐chinned petrels (Procellaria aequinoctialis ) with very high levels of tick (Ixodes kerguelenensis ) infestation on both eyes. This degree of infestation was likely responsible for the birds’ death. Although this rare observation may seem anecdotal, it reveals that ticks can be fatal for a long‐lived colonial seabird species, in this case one that is already under pressure from fisheries bycatch and predation by introduced black rats (Rattus rattus ). It also raises questions about the frequency and spatial distribution of such a phenomenon and the conditions that may have been responsible for its occurrence. Such high parasite loads imply high local tick abundances but also a lack of preening by the partner. Could this be linked to the recent death of the partner? Infestations by ticks can affect the health of hosts through blood loss, the injection of toxins, and the transmission of infectious agents. In this instance, the mechanical blocking of eyesight may also have affected the birds’ behavior. The potential impact of climate change on local parasitic infestation levels is another important question. Parasites and diseases can harm endangered species in polar and subpolar areas, and could play critical roles in some circumstances.
Programme: 1151
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Crouzet N., Mékarnia D., Agabi K., Guillot T., Abe L., Bayliss D., Deeg H., Murgas F., Palle E., Schmider F. (2020). Searching for long period transiting exoplanets with ASTEP South at Dome C, Antarctica. Bachelor's thesis, , .
Abstract: Much of our understanding of gas giant exoplanets come from those transiting in front of bright stars at short orbital separations (P ~ 3 days, a ~ 0.05 au). However, these
Programme: 1066
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Martischang J-P. (2020). Exoplanètes : sélection de calibrateurs et ajustements de transits. Bachelor's thesis, , .
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Crouzet, N., Guillot T., Abe L., Mékarnia D., Agabi A., Schmider F.-X., Vauglin I. (2020). Astronomie à Concordia : projets et besoins. Bachelor's thesis, , .
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Guillot T. (2020). Discovering Exoplanets from Antarctica with ASTEP. Bachelor's thesis, , .
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Crouzet N., et al. (2020). Towards ASTEP+, a two-color photometric telescope at Dome C, Antarctica (Vol. Paper 11447-23). Bachelor's thesis, , .
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Philippe Ricaud, Paolo Grigioni, Romain Roehrig, Pierre Durand, Dana E. Veron. (2020). Trends in Atmospheric Humidity and Temperature above Dome C, Antarctica Evaluated from Observations and Reanalyses (Vol. 11). Bachelor's thesis, , .
Abstract: The time evolution of humidity and temperature above Dome C (Antarctica) has been investigated by considering data from (1) meteorological radiosondes (2005–2017), (2) the microwave radiometer HAMSTRAD (2012–2017), (3) four modern meteorological reanalyses (1980–2017) and (4) the southern annular mode (SAM) index (1980–2017). From these observations (2005–2017), a significant moistening trend (0.08 ± 0.06 kg m−2 dec−1) is associated with a significant warming trend (1.08 ± 0.55 K dec−1) in summer. Conversely, a significant drying trend of −0.04 ± 0.03 kg m−2 dec−1 (−0.05 ± 0.03 kg m−2 dec−1) is associated with a significant cooling trend of −2.4 ± 1.2 K dec−1 (−5.1 ± 2.0 K dec−1) in autumn (winter), with no significant trends in the spring. We demonstrate that 1) the trends identified in the radiosondes (2005–2017) are also present in the reanalyses and 2) the multidecadal variability of integrated water vapor and near-surface temperature (1980–2017) is strongly influenced by variability in the SAM index for all seasons but spring. Our study suggests that the decadal trends observed in humidity and near-surface temperature at Dome C (2005–2017) reflect the multidecadal variability of the atmosphere, and are not indicative of long-term trends that may be related to global climate change.
Keywords: meteorological reanalyses microwave radiometer precipitable water radiosondes SAM index temperature trends
Programme: 910
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