J. Rojas, J. Duprat, C. Engrand, E. Dartois, L. Delauche, M. Godard, M. Gounelle, J. D. Carrillo-Sánchez, P. Pokorný, J. M. C. Plane. (2021). The micrometeorite flux at Dome C (Antarctica), monitoring the accretion of extraterrestrial dust on Earth (Vol. 560).
Abstract: The annual flux of extraterrestrial material on Earth is largely dominated by sub-millimetre particles. The mass distribution and absolute value of this cosmic dust flux at the Earth's surface is however still uncertain due to the difficulty in monitoring both the collection efficiency and the exposure parameter (i.e. the area-time product in m2.yr). In this paper, we present results from micrometeorite collections originating from the vicinity of the CONCORDIA Station located at Dome C (Antarctica), where we performed several independent melts of large volumes of ultra-clean snow. The regular precipitation rate and the exceptional cleanliness of the snow from central Antarctica allow a unique control on both the exposure parameter and the collection efficiency. A total of 1280 unmelted micrometeorites (uMMs) and 808 cosmic spherules (CSs) with diameters ranging from 30 to 350 μm were identified. Within that size range, we measured mass fluxes of 3.0 μg.m−2.yr−1 for uMMs and 5.6 μg.m−2.yr−1 for CSs. Extrapolated to the global flux of particles in the 12-700 μm diameter range, the mass flux of dust at Earth's surface is 5,200±12001500 tons.yr−1 (1,600±500 and 3,600±7001000 tons.yr−1 of uMMs and CSs, respectively). We indicate the statistical uncertainties expected for collections with exposure parameters in the range of 0.1 up to 105 m2.yr. In addition, we estimated the flux of altered and unaltered carbon carried by heated and un-heated particles at Earth's surface. The mass distributions of CSs and uMMs larger than 100 μm are fairly well reproduced by the CABMOD-ZoDy model that includes melting and evaporation during atmospheric entry of the interplanetary dust flux. These numerical simulations suggest that most of the uMMs and CSs originate from Jupiter family comets and a minor part from the main asteroid belt. The total dust mass input before atmospheric entry is estimated at 15,000 tons.yr−1. The existing discrepancy between the flux data and the model for uMMs below 100 μm suggests that small fragile uMMs may evade present day collections, and/or that the amount of small interplanetary particles at 1 AU may be smaller than expected.
Keywords: Antarctic micrometeorites atmospheric entry cosmic spherules extraterrestrial flux interplanetary dust particles zodiacal cloud
Programme: 1120
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Jacques Labonne, Aurélie Manicki, Louise Chevalier, Marin Tétillon, François Guéraud, Andrew P. Hendry. (2021). Using Reciprocal Transplants to Assess Local Adaptation, Genetic Rescue, and Sexual Selection in Newly Established Populations (Vol. 12).
Abstract: Small populations establishing on colonization fronts have to adapt to novel environments with limited genetic variation. The pace at which they can adapt, and the influence of genetic variation on their success, are key questions for understanding intraspecific diversity. To investigate these topics, we performed a reciprocal transplant experiment between two recently founded populations of brown trout in the sub-Antarctic Kerguelen Islands. Using individual tagging and genetic assignment methods, we tracked the fitness of local and foreign individuals, as well as the fitness of their offspring over two generations. In both populations, although not to the same extent, gene flow occurred between local and foreign gene pools. In both cases, however, we failed to detect obvious footprints of local adaptation (which should limit gene flow) and only weak support for genetic rescue (which should enhance gene flow). In the population where gene flow from foreign individuals was low, no clear differences were observed between the fitness of local, foreign, and F1 hybrid individuals. In the population where gene flow was high, foreign individuals were successful due to high mating success rather than high survival, and F1 hybrids had the same fitness as pure local offspring. These results suggest the importance of considering sexual selection, rather than just local adaptation and genetic rescue, when evaluating the determinants of success in small and recently founded populations.
Keywords: gene flow genetic rescue local adaptation mating success small population
Programme: 1041
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Jan Grimsrud Davidsen, Xavier Bordeleau, Sindre Håvarstein Eldøy, Frederick Whoriskey, Michael Power, Glenn T. Crossin, Colin Buhariwalla, Philippe Gaudin. (2021). Marine habitat use and feeding ecology of introduced anadromous brown trout at the colonization front of the sub-Antarctic Kerguelen archipelago (Vol. 11).
Abstract: In 1954, brown trout were introduced to the Kerguelen archipelago (49°S, 70°E), a pristine, sub-Antarctic environment previously devoid of native freshwater fishes. Trout began spreading rapidly via coastal waters to colonize adjacent watersheds, however, recent and unexpectedly the spread has slowed. To better understand the ecology of the brown trout here, and why their expansion has slowed, we documented the marine habitat use, foraging ecology, and environmental conditions experienced over one year by 50 acoustically tagged individuals at the colonization front. Trout mainly utilized the marine habitat proximate to their tagging site, ranging no further than 7 km and not entering any uncolonized watersheds. Nutritional indicators showed that trout were in good condition at the time of tagging. Stomach contents and isotope signatures in muscle of additional trout revealed a diet of amphipods (68%), fish (23%), isopods (6%), and zooplankton (6%). The small migration distances observed, presence of suitable habitat, and rich local foraging opportunities suggest that trout can achieve their resource needs close to their home rivers. This may explain why the expansion of brown trout at Kerguelen has slowed.
Keywords: Animal migration Behavioural ecology Ecology Stable isotope analysis
Programme: 1041
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Jana Maresova, Alena Suchackova Bartonova, Martin Konvicka, Toke T. Høye, Olivier Gilg, Jean-Claude Kresse, Nazar A. Shapoval, Roman V. Yakovlev, Zdenek Faltynek Fric. (2021). The story of endurance: Biogeography and the evolutionary history of four Holarctic butterflies with different habitat requirements (Vol. 48).
Abstract: Aim Biogeographical studies on the entire ranges of widely distributed species can change our perception of species’ range dynamics. We studied the effects of Pleistocene glacial cycles on current butterfly species distributions, aiming to uncover complex biogeographic patterns in the Holarctic, a region dramatically affected by Cenozoic climate change. Location Eurasia and North America. Taxon Boloria chariclea, Agriades optilete, Carterocephalus palaemon, Oeneis jutta. Methods We reconstructed the biogeographic history of four butterfly species differing in habitat preferences (B. chariclea – tundra, A. optilete – bogs, C. palaemon – temperate grasslands, O. jutta – taiga), using one mitochondrial and two nuclear DNA markers and species distribution modelling. Results Except for B. chariclea, all species originated in Eurasia. The open habitat species A. optilete and C. palaemon formed widely distributed east-west genetic clusters in continental Asia and clusters separated from them in Europe. Genetic clusters of the taiga species O. jutta were not geographically separated in Eurasia, suggesting Pleistocene fragmentation and recent reconnection. The glaciated North America was recolonized from Beringian and southerly situated refugia by all four species. Main conclusions The Pleistocene mammoth steppe allowed a widespread continuous distribution of open habitat butterflies, while in contrast the distribution of a taiga-specialist species was more limited. In the mostly flat and continental North Asia, the butterflies of various types of open habitats survived ice age in widely distributed east-west belts. In the mountainous and oceanic regions of Europe, Beringia and west North America, all four species persisted in contracted areas during the glacials. After deglaciation, they expanded their ranges and formed contact zones among populations. To conclude, the harsh climate of the glacials did not represent an obstacle for butterflies. Instead, different habitat specialists selected their own ways to thrive in the dynamic conditions of Quaternary glacial periods.
Keywords: COI Ef-1α insect Lepidoptera mammoth steppe Pleistocene Quaternary RpS5 species distribution modelling
Programme: 1036
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Jean Roger, Bernard Pelletier, Maxime Duphil, Jérôme Lefèvre, Jérôme Aucan, Pierre Lebellegard, Bruce Thomas, Céline Bachelier, David Varillon. (2021). The Mw 7.5 Tadine (Maré, Loyalty Is.) earthquake and related tsunami of December 5, 2018: implications for tsunami hazard assessment in New Caledonia.
Abstract: On The 5th Of December 2018, A Magnitude Mw 7.5 Earthquake Occurred Southeast Of Maré, An Island Of The Loyalty Archipelago, New Caledonia. This Earthquake Is Located At The Junction Between The Plunging Loyalty Ridge And The Southernmost Vanuatu Arc, In A Tectonically Very Active Area Regularly Subjected To Strong Seismic Crises And Events Higher Than Magnitude 7 And Up To 8. Widely Felt In New Caledonia It Has Been Immediately Followed By A Tsunami Warning, Confirmed Shortly After By A First Wave Arrival At The Loyalty Islands Tide Gauges (Maré And Lifou), Then Along The East Coast Of Grande Terre Of New Caledonia And In Several Islands Of The Vanuatu Archipelago. Seafloor Initial Deformation Linked To Tsunami Generation Has Been Modeled With Most Numerical Code Using Earthquake Parameters Available From Seismic Observatories. Then The Wave Propagation Has Been Modeled Using Schism, Another Modelling Code Solving The Shallow Water Equations On An Unstructured Grid Based On A New Regional Dem Of ~180 M Resolution And Allowing Refinement In Many Critical Areas. Finally, The Results Have Been Compared To Tide Gauge Records, Field Observations And Testimonials From 2018. The Arrival Times, Wave Amplitude And Polarities Present Good Similarities, Especially In Far-field Locations (Hienghène, Port-vila And Poindimié). Maximum Wave Heights And Energy Maps For Two Different Scenarios Highlight The Fact That The Orientation Of The Source (Strike Of The Rupture) Played An Important Role, Focusing The Maximum Energy Path Of The Tsunami South Of Grande-terre And The Isle Of Pines. However, Both Scenarios Indicate Similar Propagation Toward Aneityum, Vanuatu Southernmost Island, The Bathymetry Acting Like A Waveguide. This Study Has A Significant Implication In Tsunami Hazard Mitigation In New Caledonia As It Helps To Validate The Modelling Code And Process Used To Prepare A Scenarios Database For Warning And Coastal Evacuation.
Programme: 133
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Jean-Pierre Féral, Marc Verlaque, Sebastián Rosenfeld, Elie Poulin, Anne Chenuil, Thomas Saucède. (2021). The Marine Vegetation of the Kerguelen Islands: History of Scientific Campaigns, Inventory of the Flora and First Analysis of Its Biogeographical Affinities (Vol. 42).
Abstract: Conceived as a baseline for the management and conservation of the marine protected area of the French Southern Territories (réserve naturelle nationale des Terres australes françaises), the checklist of marine macroalgae of the Kerguelen Islands was updated based on an extensive review of the literature and scientific databases, from the first report of the Ross expedition, in 1840, to the most recent works. This work was also conceived as a starting point for forthcoming investigations using molecular systematics tools and for monitoring the effects of global change on sub-Antarctic marine ecosystems. After a brief history of scientific campaigns, a list of 166 species was established (103 Rhodophyta, 35 Chlorophyta and 28 Ochrophyta [Phaeophyceae]). Molecular systematics studiess have shown the existence of recurrent discrepancies between the established, morphology-based taxonomy and molecular species delimitation, calling for a revision of systematics. Nevertheless, a first analysis of biogeographical affinities of the marine flora of the Kerguelen Islands is carried out and preliminary results are partially congruent with the main regions currently recognized in the Southern Ocean suggesting the importance of long-distance dispersal to explain the observed distribution patterns.
Programme: 1044
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Jennifer A. Burt, Diana Dragomir, Paul Mollière, Allison Youngblood, Antonio García Muñoz, John McCann, Laura Kreidberg, Chelsea X. Huang, Karen A. Collins, Jason D. Eastman, Lyu Abe, Jose M. Almenara, Ian J. M. Crossfield, Carl Ziegler, Joseph E. Rodriguez, Eric E. Mamajek, Keivan G. Stassun, Samuel P. Halverson, Steven Villanueva, R. Paul Butler, Sharon Xuesong Wang, Richard P. Schwarz, George R. Ricker, Roland Vanderspek, David W. Latham, S. Seager, Joshua N. Winn, Jon M. Jenkins, Abdelkrim Agabi, Xavier Bonfils, David Ciardi, Marion Cointepas, Jeffrey D. Crane, Nicolas Crouzet, Georgina Dransfield, Fabo Feng, Elise Furlan, Tristan Guillot, Arvind F. Gupta, Steve B. Howell, Eric L. N. Jensen, Nicholas Law, Andrew W. Mann, Wenceslas Marie-Sainte, Rachel A. Matson, Elisabeth C. Matthews, Djamel Mékarnia, Joshua Pepper, Nic Scott, Stephen A. Shectman, Joshua E. Schlieder, François-Xavier Schmider, Daniel J. Stevens, Johanna K. Teske, Amaury H. M. J. Triaud, David Charbonneau, Zachory K. Berta-Thompson, Christopher J. Burke, Tansu Daylan, Thomas Barclay, Bill Wohler, C. E. Brasseur. (2021). TOI-1231 b: A Temperate, Neptune-sized Planet Transiting the Nearby M3 Dwarf NLTT 24399 (Vol. 162).
Abstract: We report the discovery of a transiting, temperate, Neptune-sized exoplanet orbiting the nearby (d = 27.5 pc), M3V star TOI-1231 (NLTT 24399, L 248-27, 2MASS J10265947-5228099). The planet was detected using photometric data from the Transiting Exoplanet Survey Satellite and followed up with observations from the Las Cumbres Observatory and the Antarctica Search for Transiting ExoPlanets program. Combining the photometric data sets, we find that the newly discovered planet has a radius of and an orbital period of 24.246 days. Radial velocity measurements obtained with the Planet Finder Spectrograph on the Magellan Clay telescope confirm the existence of the planet and lead to a mass measurement of 15.5 ± 3.3 M ⊕. With an equilibrium temperature of just 330 K, TOI-1231 b is one of the coolest small planets accessible for atmospheric studies thus far, and its host star’s bright near-infrared brightness (J = 8.88, K s = 8.07) makes it an exciting target for the Hubble Space Telescope and the James Webb Space Telescope. Future atmospheric observations would enable the first comparative planetology efforts in the 250–350 K temperature regime via comparisons with K2-18 b. Furthermore, TOI-1231's high systemic radial velocity (70.5 km s−1) may allow for the detection of low-velocity hydrogen atoms escaping the planet by Doppler, shifting the H i Lyα stellar emission away from the geocoronal and interstellar medium absorption features.
Programme: 1066
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Jérémy Tornos. (2021). Approches intégrées en écologie de la conservation des oiseaux marins : cas de l’utilisation d'autovaccins pour la conservation des albatros sur l'île d'Amsterdam.
Abstract: L’Albatros à nez jaune de l’océan indien (Thalassarche carteri) est une espèce menacée d’extinction dont la population principale, qui se reproduit sur l’île Amsterdam (Terres Australes et Antarctiques Françaises), connait un déclin et une très forte mortalité des jeunes individus depuis plusieurs décennies. La bactérie responsable du choléra aviaire, Pasteurella multocida, est suspectée comme étant à l'origine de ces mortalités et notre équipe évalue depuis plusieurs années maintenant l'utilisation d'un vaccin pour protéger les poussins, via leur vaccination directe, mais aussi celle des femelles reproductrices susceptibles de transmettre des anticorps protecteurs à leur poussin. Le vaccin utilisé est un vaccin autologue (autovaccin) spécifiquement développé par Ceva-Biovac contre une souche de la bactérie Pasteurella multocida isolée sur cadavre d’albatros. Suite à l’obtention de premiers résultats prometteurs, les objectifs de la thèse étaient d’ajuster le protocole de vaccination, mais également de mieux appréhender et décrire les processus éco-épidémiologiques en jeu au sein des populations de vertébrés de l’île Amsterdam. Ceci a reposé sur l'analyse fine du suivi de couples reproducteurs année après année, mais aussi sur l'utilisation de données éco-épidémiologiques expérimentales complémentaires, notamment une nouvelle formulation du vaccin. Une diversité de pathogènes responsables de mortalités a pu être caractérisée. L’âge optimal de vaccination des poussins parait être vers 10 jours et la vaccination des femelles reproductrices semble pouvoir protéger les poussins pendant plusieurs années, mais la forte densité de rats (Rattus norvegicus) actifs dans les colonies a rendu difficile l’identification d’un effet protecteur fort du vaccin. Les résultats obtenus améliorent la compréhension des mécanismes de circulation d'agents infectieux chez des espèces à reproduction coloniale et permettront de comparer les bénéfices relatifs attendus de différents scénarios de vaccination. Le travail montre l’importance d’intégrer des approches complémentaires, notamment du domaine biomédical et de l’écologie des populations, pour aborder la problématique de l’émergence de maladies infectieuses dans le contexte des changements environnementaux actuels.
Programme: 1151
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Jesús A Ballesteros, Emily V W Setton, Carlos E Santibáñez-López, Claudia P Arango, Georg Brenneis, Saskia Brix, Kevin F Corbett, Esperanza Cano-Sánchez, Merai Dandouch, Geoffrey F Dilly, Marc P Eleaume, Guilherme Gainett, Cyril Gallut, Sean McAtee, Lauren McIntyre, Amy L Moran, Randy Moran, Pablo J López-González, Gerhard Scholtz, Clay Williamson, H Arthur Woods, Jakob T Zehms, Ward C Wheeler, Prashant P Sharma. (2021). Phylogenomic Resolution of Sea Spider Diversification through Integration of Multiple Data Classes (Vol. 38).
Abstract: Despite significant advances in invertebrate phylogenomics over the past decade, the higher-level phylogeny of Pycnogonida (sea spiders) remains elusive. Due to the inaccessibility of some small-bodied lineages, few phylogenetic studies have sampled all sea spider families. Previous efforts based on a handful of genes have yielded unstable tree topologies. Here, we inferred the relationships of 89 sea spider species using targeted capture of the mitochondrial genome, 56 conserved exons, 101 ultraconserved elements, and 3 nuclear ribosomal genes. We inferred molecular divergence times by integrating morphological data for fossil species to calibrate 15 nodes in the arthropod tree of life. This integration of data classes resolved the basal topology of sea spiders with high support. The enigmatic family Austrodecidae was resolved as the sister group to the remaining Pycnogonida and the small-bodied family Rhynchothoracidae as the sister group of the robust-bodied family Pycnogonidae. Molecular divergence time estimation recovered a basal divergence of crown group sea spiders in the Ordovician. Comparison of diversification dynamics with other marine invertebrate taxa that originated in the Paleozoic suggests that sea spiders and some crustacean groups exhibit resilience to mass extinction episodes, relative to mollusk and echinoderm lineages.
Programme: 1124
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Jilda Alicia Caccavo, Thierry Raclot, Timothée Poupart, Yan Ropert-Coudert, Frédéric Angelier. (2021). Anthropogenic activities are associated with shorter telomeres in chicks of Adélie penguin (Pygoscelis adeliae) (Vol. 44).
Abstract: Defining the impact of anthropogenic stressors on Antarctic wildlife is an active aim for investigators. Telomeres represent a promising molecular tool to investigate the fitness of wild populations, as their length may predict longevity and survival. We examined the relationship between telomere length and human exposure in Adélie penguin chicks (Pygoscelis adeliae) from East Antarctica. Telomere length was compared between chicks from areas with sustained human activity and on neighboring protected islands with little or no human presence. Adélie penguin chicks from sites exposed to human activity had significantly shorter telomeres than chicks from unexposed sites in nearby protected areas, with exposed chicks having on average 3.5% shorter telomeres than unexposed chicks. While sampling limitations preclude our ability to draw more sweeping conclusions at this time, our analysis nonetheless provides important insights into measures of colony vulnerability. More data are needed both to understand the proximate causes (e.g., stress, feeding events) leading to shorter telomeres in chicks from human exposed areas, as well as the fitness consequences of reduced telomere length. We suggest to further test the use of telomere length analysis as an eco-indicator of stress in wildlife among anthropized sites throughout Antarctica.
Programme: 1091
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