| Home | [1–10] << 11 12 13 14 15 16 17 18 19 20 >> [21–25] |
|
. (2021). The high diversity of Southern Ocean sea stars (Asteroidea) reveals original evolutionary pathways (Vol. 190). Bachelor's thesis, , .
Abstract: Benthic life in the Southern Ocean (SO) features unique life history traits and species assemblages, but the origin and evolution of many of these taxonomic groups is still unclear. Sea stars (Asteroidea) are a diversified and abundant component of benthic ecosystems in the SO, in which they can play key ecological roles. Former studies suggest that the diversity of the entire class is still poorly known and underestimated, hampering the assessment of the origin and evolution of the class in the SO. In the present study, we analyse spatial patterns of SO sea star diversity using an occurrence database of ~14,000 entries. The biogeographic analysis is coupled with the exploration of an extensive molecular phylogeny based on over 4,400 specimen sequences to inform, support and/or question the observed diversity patterns. We show that the current taxonomy of SO asteroids needs revision and that their diversity has generally been overlooked and misinterpreted. Molecular results highlight the recent diversification of most studied taxa, at genus and species levels, which supports an evolutionary scenario referring to successive invasion and exchange events between the SO and adjacent regions, and clade diversification during periods of rapid environmental changes driven by the succession of glacial cycles. Our work advocates for employing, and endorsing the use of extensive genetic barcode libraries for biodiversity studies.
Keywords: Antarctica Biodiversity COI mtDNA Echinodermata Evolution Phylogeography
Programme: 1044,1124
|
|
R. Olmi, M. Bittelli, G. Picard, L. Arnaud, A. Mialon, S. Priori. (2021). Investigating the influence of the grain size and distribution on the macroscopic dielectric properties of Antarctic firn (Vol. 185).
Keywords: Antarctica Close?off Dielectric measurements Dielectric model Firn Full wave EM simulations Ice cores
Programme: 1110
|
|
. (2021). Risk assessment of SARS-CoV-2 in Antarctic wildlife (Vol. 755).
Abstract: The coronavirus disease 2019 (COVID-19) pandemic is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This pathogen has spread rapidly across the world, causing high numbers of deaths and significant social and economic impacts. SARS-CoV-2 is a novel coronavirus with a suggested zoonotic origin with the potential for cross-species transmission among animals. Antarctica can be considered the only continent free of SARS-CoV-2. Therefore, concerns have been expressed regarding the potential human introduction of this virus to the continent through the activities of research or tourism to minimise the effects on human health, and the potential for virus transmission to Antarctic wildlife. We assess the reverse-zoonotic transmission risk to Antarctic wildlife by considering the available information on host susceptibility, dynamics of the infection in humans, and contact interactions between humans and Antarctic wildlife. The environmental conditions in Antarctica seem to be favourable for the virus stability. Indoor spaces such as those at research stations, research vessels or tourist cruise ships could allow for more transmission among humans and depending on their movements between different locations the virus could be spread across the continent. Among Antarctic wildlife previous in silico analyses suggested that cetaceans are at greater risk of infection whereas seals and birds appear to be at a low infection risk. However, caution needed until further research is carried out and consequently, the precautionary principle should be applied. Field researchers handling animals are identified as the human group posing the highest risk of transmission to animals while tourists and other personnel pose a significant risk only when in close proximity (< 5 m) to Antarctic fauna. We highlight measures to reduce the risk as well as identify of knowledge gaps related to this issue.
Keywords: Antarctica Coronavirus COVID-19 Mitigation measures Reverse zoonoses Transmission
Programme: 1151
|
|
A. Baranov, R. Tenzer, A. Morelli. (2021). Updated Antarctic crustal model (Vol. 89).
Keywords: Antarctica Crustal structure Gondwana Sediments
Programme: 133
|
|
Casey Youngflesh, Yun Li, Heather J. Lynch, Karine Delord, Christophe Barbraud, Rubao Ji, Stephanie Jenouvrier. (2021). Lack of synchronized breeding success in a seabird community: extreme events, niche separation, and environmental variability (Vol. 130).
Abstract: Synchrony in ecological systems, the degree to which elements respond similarly over time or space, can inform our understanding of how ecosystems function and how they are responding to global change. While studies of ecological synchrony are often focused on within-species dynamics, synchrony among species may provide important insights into how dynamics of one species are indicative of conditions relevant to the larger community, with both basic and applied implications. Ecological theory suggests there may be conditions under which communities might exhibit increased synchrony, however, the degree to which these patterns are borne out in natural systems is currently unknown. We used long-term breeding success data from a community of Antarctic seabirds to assess the degree of interspecific, community synchrony, and the role that extreme events play in driving these dynamics. We assessed theoretical links between community synchrony, niche separation, and environmental variability using data from this and three other seabird communities as well as a simulation study. Results show that reproductive success for individual species in the Antarctic seabird community fluctuated relatively independently from one another, resulting in little synchrony across this community, outside of extreme years. While an exceptionally poor year for a given species was not necessarily associated with an exceptionally poor year for any other species, one community-wide extreme year existed. When compared to other seabird communities, this group of Antarctic seabirds exhibited lower overall synchrony and higher estimated niche separation, supporting theoretical predictions. Empirical and simulation-derived results suggest that communities where temporal variation is small for conditions in which species respond substantially differently, and large for conditions in which species respond similarly, may exhibit more synchronous dynamics. Identifying where and why synchronous dynamics might be more apparent has the potential to inform how ecological communities might respond to future global change.
Keywords: Antarctica environmental indicators extreme events global change niche separation synchrony
Programme: 109
|
|
Lara D. Shepherd, Colin M. Miskelly, Yves Cherel, Alan J. D. Tennyson. (2021). Genetic identification informs on the distributions of vagrant Royal (Eudyptes schlegeli) and Macaroni (Eudyptes chrysolophus) Penguins (Vol. 44).
Keywords: Antarctica Eudyptes chrysolophus Eudyptes schlegeli Genetic identification Penguin distribution Predation
Programme: 109
|
|
. (2021). Fifty million years of beetle evolution along the Antarctic Polar Front (Vol. 118).
Keywords: Antarctica herbivory island biogeography paleoclimate species radiation
Programme: 136
|
|
Natasha Roy, James Woollett, Najat Bhiry, Isabel Lemus-Lauzon, Ann Delwaide, Dominique Marguerie. (2021). Anthropogenic and climate impacts on subarctic forests in the Nain region, Nunatsiavut: Dendroecological and historical approaches (Vol. 28).
Programme: 1080
|
|
. (2021). Snow hardness impacts intranivean locomotion of arctic small mammals (Vol. 12).
Abstract: Fossorial locomotion is often considered as the most energetically costly of all terrestrial locomotion. Small arctic rodents, such as lemmings, dig tunnels not only in the soil but also through the snowpack, which is present for over 8 months of the year. Lemmings typically dig in the softest snow layer called the depth hoar but with climate change, melt-freeze and rain-on-snow (ROS) events are expected to increase in the Arctic, leading to a higher frequency of hardened snowpacks. We assessed the impacts of snow hardness on the locomotion of two lemming species showing different morphological adaptations for digging. We hypothesized that an increase in snow hardness would (1) decrease lemming performance and (2) increase their effort while digging, but those responses would differ between lemming species. We exposed four brown lemmings (Lemmus trimucronatus) and three collared lemmings (Dicrostonyx groenlandicus) to snow of different hardness (soft, hard, and ROS) during 30-min trials (n = 63 trials) in a cold room and filmed their behavior. We found that the digging speed and tunnel length of both species decreased with snow hardness and density, underlining the critical role of snow properties in affecting lemming digging performance. During the ROS trials, time spent digging by lemmings increased considerably and they also started using their incisors to help break the hard snow, validating our second hypothesis. Overall, digging performance was higher in collared lemmings, the species showing more morphological adaptations to digging, than in brown lemmings. We conclude that the digging performance of lemming is highly dependent on snowpack hardness and that the anticipated increase in ROS events may pose a critical energetic challenge for arctic rodent populations.
Keywords: Arctic burrowing behavior digging fossorial hardness lemming locomotion rain-on-snow rodent snow subnivean tunnel
Programme: 1042
|
|
. (2021). (Vol. 13).
Abstract: The global climate shift currently underway has significant impacts on both the quality and quantity of snow precipitation. This directly influences the spatial variability of the snowpack as well as cumulative snow height. Contemporary glacier retreat reorganizes periglacial morphology: while the glacier area decreases, the moraine area increases. The latter is becoming a new water storage potential that is almost as important as the glacier itself, but with considerably more complex topography. Hence, this work fills one of the missing variables of the hydrological budget equation of an arctic glacier basin by providing an estimate of the snow water equivalent (SWE) of the moraine contribution. Such a result is achieved by investigating Structure from Motion (SfM) image processing that is applied to pictures collected from an Unmanned Aerial Vehicle (UAV) as a method for producing snow depth maps over the proglacial moraine area. Several UAV campaigns were carried out on a small glacial basin in Spitsbergen (Arctic): the measurements were made at the maximum snow accumulation season (late April), while the reference topography maps were acquired at the end of the hydrological year (late September) when the moraine is mostly free of snow. The snow depth is determined from Digital Surface Model (DSM) subtraction. Utilizing dedicated and natural ground control points for relative positioning of the DSMs, the relative DSM georeferencing with sub-meter accuracy removes the main source of uncertainty when assessing snow depth. For areas where snow is deposited on bare rock surfaces, the correlation between avalanche probe in-situ snow depth measurements and DSM differences is excellent. Differences in ice covered areas between the two measurement techniques are attributed to the different quantities measured: while the former only measures snow accumulation, the latter includes all of the ice accumulation during winter through which the probe cannot penetrate, in addition to the snow cover. When such inconsistencies are observed, icing thicknesses are the source of the discrepancy that is observed between avalanche probe snow cover depth measurements and differences of DSMs.
Keywords: arctic cryosphere moraine photogrammetry snow water equivalent snowcover spatial dynamics UAV-SfM
Programme: 1108
|