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Amandine Gamble, Romain Bazire, Karine Delord, Christophe Barbraud, Audrey Jaeger, Hubert Gantelet, Eric Thibault, Camille Lebarbenchon, Erwan Lagadec, Pablo Tortosa, Henri Weimerskirch, Jean-Baptiste Thiebot, Romain Garnier, Jérémy Tornos, Thierry Boulinier. (2020). Predator and scavenger movements among and within endangered seabird colonies: Opportunities for pathogen spread (Vol. 57). Bachelor's thesis, , .
Abstract: The spatial structure of host communities is expected to constrain pathogen spread. However, predators and/or scavengers may connect distant host (sub)populations when foraging. Determining whether some individuals or populations play a prominent role in the spread of pathogens is critical to inform management measures. We explored movements and epidemiological status of brown skuas Stercorarius antarcticus, the only avian terrestrial consumer native of Amsterdam Island (Indian Ocean), to assess whether and how they could be involved in the spread of the bacterium Pasteurella multocida, which recurrently causes avian cholera outbreaks in endangered albatross and penguin species breeding on the island. High proportions of seropositive and DNA-positive individuals for P. multocida indicated that skuas are highly exposed to the pathogen and may be able to transmit it. Movement tracking revealed that the foraging ranges of breeding skuas largely overlap among individuals and expand all along the coasts where albatrosses and penguins nest, but not on the inland plateau hosting the endemic Amsterdam albatross Diomedea amsterdamensis. Considering the epidemiological and movement data, skua movements may provide opportunity for pathogen spread among and within seabird colonies. Synthesis and applications. This work highlights the importance of considering the behaviour and epidemiological status of predators and scavengers in disease dynamics because the foraging movements of individuals of such species can potentially limit the efficiency of local management measures in spatially structured host communities. Such species could thus represent priority vaccination targets to implement efficient management measures aiming at limiting pathogen spread and also be used as sentinels to monitor pathogen circulation and evaluate the effectiveness of management measures.
Keywords: conservation biology disease ecology dynamic space utilization individual heterogeneity movement ecology Pasteurella multocida sentinel species serology
Programme: 109,1151
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Julie Mestre, Matthieu Authier, Yves Cherel, Rob Harcourt, Clive R. McMahon, Mark A. Hindell, Jean-Benoît Charrassin, Christophe Guinet. (2020). Decadal changes in blood δ13C values, at-sea distribution, and weaning mass of southern elephant seals from Kerguelen Islands (Vol. 287). Bachelor's thesis, , .
Abstract: Changes in the foraging environment and at-sea distribution of southern elephant seals from Kerguelen Islands were investigated over a decade (2004–2018) using tracking, weaning mass, and blood δ13C values. Females showed either a sub-Antarctic or an Antarctic foraging strategy, and no significant shift in their at-sea distribution was detected between 2004 and 2017. The proportion of females foraging in sub-Antarctic versus Antarctic habitats did not change over the 2006–2018 period. Pup weaning mass varied according to the foraging habitat of their mothers. The weaning mass of sub-Antarctic foraging mothers' pups decreased by 11.7 kg over the study period, but they were on average 5.8 kg heavier than pups from Antarctic foraging mothers. Pup blood δ13C values decreased by 1.1‰ over the study period regardless of their sex and the presumed foraging habitat of their mothers. Together, these results suggest an ecological change is occurring within the Indian sector of the Southern Ocean with possible consequences on the foraging performance of southern elephant seals. We hypothesize that this shift in δ13C is related to a change in primary production and/or in the composition of phytoplankton communities, but this requires further multidisciplinary investigations.
Keywords: bio-logging decadal change foraging habitat Indian sector of the Southern Ocean population strategies stable isotopes
Programme: 109,1201
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Hila Levy, Steven R Fiddaman, Juliana A Vianna, Daly Noll, Gemma V Clucas, Jasmine K H Sidhu, Michael J Polito, Charles A Bost, Richard A Phillips, Sarah Crofts, Gary D Miller, Pierre Pistorius, Francesco Bonnadonna, Céline Le Bohec, Andrés Barbosa, Phil Trathan, Andrea Raya Rey, Laurent A F Frantz, Tom Hart, Adrian L Smit. (2020). Evidence of Pathogen-Induced Immunogenetic Selection across the Large Geographic Range of a Wild Seabird (Vol. 37). Bachelor's thesis, , .
Abstract: Over evolutionary time, pathogen challenge shapes the immune phenotype of the host to better respond to an incipient threat. The extent and direction of this selection pressure depend on the local pathogen composition, which is in turn determined by biotic and abiotic features of the environment. However, little is known about adaptation to local pathogen threats in wild animals. The Gentoo penguin (Pygoscelis papua) is a species complex that lends itself to the study of immune adaptation because of its circumpolar distribution over a large latitudinal range, with little or no admixture between different clades. In this study, we examine the diversity in a key family of innate immune genes—the Toll-like receptors (TLRs)—across the range of the Gentoo penguin. The three TLRs that we investigated present varying levels of diversity, with TLR4 and TLR5 greatly exceeding the diversity of TLR7. We present evidence of positive selection in TLR4 and TLR5, which points to pathogen-driven adaptation to the local pathogen milieu. Finally, we demonstrate that two positively selected cosegregating sites in TLR5 are sufficient to alter the responsiveness of the receptor to its bacterial ligand, flagellin. Taken together, these results suggest that Gentoo penguins have experienced distinct pathogen-driven selection pressures in different environments, which may be important given the role of the Gentoo penguin as a sentinel species in some of the world’s most rapidly changing environments.
Keywords: immunogenetics, positive selection, Toll-like receptors, pathogen-mediated selection, Antarctica and Southern Ocean, Gentoo penguin
Programme: 137,354
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Juliana A. Vianna, Flávia A. N. Fernandes, María José Frugone, Henrique V. Figueiró, Luis R. Pertierra, Daly Noll, Ke Bi, Cynthia Y. Wang-Claypool, Andrew Lowther, Patricia Parker, Celine Le Bohec, Francesco Bonadonna, Barbara Wienecke, Pierre Pistorius, Antje Steinfurth, Christopher P. Burridge, Gisele P. M. Dantas, Elie Poulin, W. Brian Simison, Jim Henderson, Eduardo Eizirik, Mariana F. Nery, Rauri C. K. Bowie. (2020). Genome-wide analyses reveal drivers of penguin diversification (Vol. 117). Bachelor's thesis, , .
Abstract: Penguins are the only extant family of flightless diving birds. They currently comprise at least 18 species, distributed from polar to tropical environments in the Southern Hemisphere. The history of their diversification and adaptation to these diverse environments remains controversial. We used 22 new genomes from 18 penguin species to reconstruct the order, timing, and location of their diversification, to track changes in their thermal niches through time, and to test for associated adaptation across the genome. Our results indicate that the penguin crown-group originated during the Miocene in New Zealand and Australia, not in Antarctica as previously thought, and that Aptenodytes is the sister group to all other extant penguin species. We show that lineage diversification in penguins was largely driven by changing climatic conditions and by the opening of the Drake Passage and associated intensification of the Antarctic Circumpolar Current (ACC). Penguin species have introgressed throughout much of their evolutionary history, following the direction of the ACC, which might have promoted dispersal and admixture. Changes in thermal niches were accompanied by adaptations in genes that govern thermoregulation and oxygen metabolism. Estimates of ancestral effective population sizes (Ne) confirm that penguins are sensitive to climate shifts, as represented by three different demographic trajectories in deeper time, the most common (in 11 of 18 penguin species) being an increased Ne between 40 and 70 kya, followed by a precipitous decline during the Last Glacial Maximum. The latter effect is most likely a consequence of the overall decline in marine productivity following the last glaciation.
Keywords: ancestral distribution ancestral niche Antarctica genome penguin
Programme: 137,354
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Hanane Marif, Jean Lilensten. (2020). Suprathermal electron moments in the ionosphere (Vol. 10). Bachelor's thesis, , .
Abstract: The ionospheric electron population is divided into two groups. The ambient electrons are thermalized. Their energy is usually smaller than one electron volt. Their densities and temperatures are the usual ones measured by incoherent scatter radars, or modeled by international codes such as International Reference Ionosphere (IRI). There is however a second population called the suprathermal electrons. This one is either due to photoionization or to electron impact between the thermosphere and the precipitation in the high latitude zone. In the frame of space weather, it may be the source of scintillations, plasma bulks and other physical phenomena. The suprathermal electron population can only indirectly be measured through the plasmaline and had never been modeled. Its modeling requires the computation of the electron stationary flux by solving the Boltzmann transport equation. This flux is multiplied by various powers of the velocity v and integrated to obtain the different order moments. By integrating f over v0dv, one deduces the suprathermal electron density. An integration of v1fdv allows the computation of their mean velocity. Higher moments give access to their temperature and finally to their heat flux. In this work, we demonstrate for the first time the full and rigorous calculation of the ionospheric electron moments up to three. As two case studies, we focus on high latitude in the auroral oval and low magnetic latitude over Algiers for different solar and geophysical conditions. We compare the suprathermal densities and temperatures to the thermal electron parameters. Our results highlight that – as expected – the suprathermal density is small compared to the thermal one. Although it is close to 3 × 103 m−3 at 180 km during the day, it drops drastically at night, to hardly reach 3 m−3. Contrarily to the density, the velocity is about 10 times more important during the nighttime when precipitation occurs than during the daytime under the electromagnetic solar flux. At 400 km, it varies during the day between 700,000 m s−1 (active solar conditions) and 900,000 m s−1 (quiet Sun). At night, the velocity varies between 3 × 106 m s−1 (low mean energy precipitation) and 3 × 107 m s−1 (high mean energy precipitation) at 400 km. The suprathermal temperature increases as the solar activity decreases or as the mean energy of the electron precipitation increases. It may reach values close to 3 × 108 K. The heat flux may be fully oriented downward or experiences a reversal with some flux going up depending on the forcing.
Programme: 1026
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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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Yan Ropert-Coudert, Anton P. Van de Putte, Ryan R. Reisinger, Horst Bornemann, Jean-Benoît Charrassin, Daniel P. Costa, Bruno Danis, Luis A. Hückstädt, Ian D. Jonsen, Mary-Anne Lea, David Thompson, Leigh G. Torres, Philip N. Trathan, Simon Wotherspoon, David G. Ainley, Rachael Alderman, Virginia Andrews-Goff, Ben Arthur, Grant Ballard, John Bengtson, Marthán N. Bester, Arnoldus Schytte Blix, Lars Boehme, Charles-André Bost, Peter Boveng, Jaimie Cleeland, Rochelle Constantine, Robert J. M. Crawford, Luciano Dalla Rosa, P. J. Nico de Bruyn, Karine Delord, Sébastien Descamps, Mike Double, Louise Emmerson, Mike Fedak, Ari Friedlaender, Nick Gales, Mike Goebel, Kimberly T. Goetz, Christophe Guinet, Simon D. Goldsworthy, Rob Harcourt, Jefferson T. Hinke, Kerstin Jerosch, Akiko Kato, Knowles R. Kerry, Roger Kirkwood, Gerald L. Kooyman, Kit M. Kovacs, Kieran Lawton, Andrew D. Lowther, Christian Lydersen, Phil O’B Lyver, Azwianewi B. Makhado, Maria E. I. Márquez, Birgitte I. McDonald, Clive R. McMahon, Monica Muelbert, Dominik Nachtsheim, Keith W. Nicholls, Erling S. Nordøy, Silvia Olmastroni, Richard A. Phillips, Pierre Pistorius, Joachim Plötz, Klemens Pütz, Norman Ratcliffe, Peter G. Ryan, Mercedes Santos, Colin Southwell, Iain Staniland, Akinori Takahashi, Arnaud Tarroux, Wayne Trivelpiece, Ewan Wakefield, Henri Weimerskirch, Barbara Wienecke, José C. Xavier, Ben Raymond, Mark A. Hindell. (2020). The retrospective analysis of Antarctic tracking data project (Vol. 7). Bachelor's thesis, , .
Abstract: The Retrospective Analysis of Antarctic Tracking Data (RAATD) is a Scientific Committee for Antarctic Research project led jointly by the Expert Groups on Birds and Marine Mammals and Antarctic Biodiversity Informatics, and endorsed by the Commission for the Conservation of Antarctic Marine Living Resources. RAATD consolidated tracking data for multiple species of Antarctic meso- and top-predators to identify Areas of Ecological Significance. These datasets and accompanying syntheses provide a greater understanding of fundamental ecosystem processes in the Southern Ocean, support modelling of predator distributions under future climate scenarios and create inputs that can be incorporated into decision making processes by management authorities. In this data paper, we present the compiled tracking data from research groups that have worked in the Antarctic since the 1990s. The data are publicly available through biodiversity.aq and the Ocean Biogeographic Information System. The archive includes tracking data from over 70 contributors across 12 national Antarctic programs, and includes data from 17 predator species, 4060 individual animals, and over 2.9 million observed locations.
Programme: 109,1091,1201
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Mark A. Hindell, Ryan R. Reisinger, Yan Ropert-Coudert, Luis A. Hückstädt, Philip N. Trathan, Horst Bornemann, Jean-Benoît Charrassin, Steven L. Chown, Daniel P. Costa, Bruno Danis, Mary-Anne Lea, David Thompson, Leigh G. Torres, Anton P. Van de Putte, Rachael Alderman, Virginia Andrews-Goff, Ben Arthur, Grant Ballard, John Bengtson, Marthán N. Bester, Arnoldus Schytte Blix, Lars Boehme, Charles-André Bost, Peter Boveng, Jaimie Cleeland, Rochelle Constantine, Stuart Corney, Robert J. M. Crawford, Luciano Dalla Rosa, P. J. Nico de Bruyn, Karine Delord, Sébastien Descamps, Mike Double, Louise Emmerson, Mike Fedak, Ari Friedlaender, Nick Gales, Michael E. Goebel, Kimberly T. Goetz, Christophe Guinet, Simon D. Goldsworthy, Rob Harcourt, Jefferson T. Hinke, Kerstin Jerosch, Akiko Kato, Knowles R. Kerry, Roger Kirkwood, Gerald L. Kooyman, Kit M. Kovacs, Kieran Lawton, Andrew D. Lowther, Christian Lydersen, Phil O’B Lyver, Azwianewi B. Makhado, Maria E. I. Márquez, Birgitte I. McDonald, Clive R. McMahon, Monica Muelbert, Dominik Nachtsheim, Keith W. Nicholls, Erling S. Nordøy, Silvia Olmastroni, Richard A. Phillips, Pierre Pistorius, Joachim Plötz, Klemens Pütz, Norman Ratcliffe, Peter G. Ryan, Mercedes Santos, Colin Southwell, Iain Staniland, Akinori Takahashi, Arnaud Tarroux, Wayne Trivelpiece, Ewan Wakefield, Henri Weimerskirch, Barbara Wienecke, José C. Xavier, Simon Wotherspoon, Ian D. Jonsen, Ben Raymond. (2020). Tracking of marine predators to protect Southern Ocean ecosystems (Vol. 580). Bachelor's thesis, , .
Abstract: Southern Ocean ecosystems are under pressure from resource exploitation and climate change1,2. Mitigation requires the identification and protection of Areas of Ecological Significance (AESs), which have so far not been determined at the ocean-basin scale. Here, using assemblage-level tracking of marine predators, we identify AESs for this globally important region and assess current threats and protection levels. Integration of more than 4,000 tracks from 17 bird and mammal species reveals AESs around sub-Antarctic islands in the Atlantic and Indian Oceans and over the Antarctic continental shelf. Fishing pressure is disproportionately concentrated inside AESs, and climate change over the next century is predicted to impose pressure on these areas, particularly around the Antarctic continent. At present, 7.1% of the ocean south of 40°S is under formal protection, including 29% of the total AESs. The establishment and regular revision of networks of protection that encompass AESs are needed to provide long-term mitigation of growing pressures on Southern Ocean ecosystems.
Programme: 394,1091,1182,1201
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Lia Siegelman, Patrice Klein, Pascal Rivière, Andrew F. Thompson, Hector S. Torres, Mar Flexas, Dimitris Menemenlis. (2020). Enhanced upward heat transport at deep submesoscale ocean fronts (Vol. 13). Bachelor's thesis, , .
Abstract: The ocean is the largest solar energy collector on Earth. The amount of heat it can store is modulated by its complex circulation, which spans a broad range of spatial scales, from metres to thousands of kilometres. In the classical paradigm, fine oceanic scales, less than 20 km in size, are thought to drive a significant downward heat transport from the surface to the ocean interior, which increases oceanic heat uptake. Here we use a combination of satellite and in situ observations in the Antarctic Circumpolar Current to diagnose oceanic vertical heat transport. The results explicitly demonstrate how deep-reaching submesoscale fronts, with a size smaller than 20 km, are generated by mesoscale eddies of size 50–300 km. In contrast to the classical paradigm, these submesoscale fronts are shown to drive an anomalous upward heat transport from the ocean interior back to the surface that is larger than other contributions to vertical heat transport and of comparable magnitude to air–sea fluxes. This effect can remarkably alter the oceanic heat uptake and will be strongest in eddy-rich regions, such as the Antarctic Circumpolar Current, the Kuroshio Extension and the Gulf Stream, all of which are key players in the climate system.
Keywords: Physical oceanography
Programme: 109,1201
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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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