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Deborah Pardo, Stéphanie Jenouvrier, Henri Weimerskirch, Christophe Barbraud. (2017). Effect of extreme sea surface temperature events on the demography of an age-structured albatross population (Vol. 372).
Abstract: Climate changes include concurrent changes in environmental mean, variance and extremes, and it is challenging to understand their respective impact on wild populations, especially when contrasted age-dependent responses to climate occur. We assessed how changes in mean and standard deviation of sea surface temperature (SST), frequency and magnitude of warm SST extreme climatic events (ECE) influenced the stochastic population growth rate log(λs) and age structure of a black-browed albatross population. For changes in SST around historical levels observed since 1982, changes in standard deviation had a larger (threefold) and negative impact on log(λs) compared to changes in mean. By contrast, the mean had a positive impact on log(λs). The historical SST mean was lower than the optimal SST value for which log(λs) was maximized. Thus, a larger environmental mean increased the occurrence of SST close to this optimum that buffered the negative effect of ECE. This ‘climate safety margin’ (i.e. difference between optimal and historical climatic conditions) and the specific shape of the population growth rate response to climate for a species determine how ECE affect the population. For a wider range in SST, both the mean and standard deviation had negative impact on log(λs), with changes in the mean having a greater effect than the standard deviation. Furthermore, around SST historical levels increases in either mean or standard deviation of the SST distribution led to a younger population, with potentially important conservation implications for black-browed albatrosses. This article is part of the themed issue ‘Behavioural, ecological and evolutionary responses to extreme climatic events’.
Programme: 109
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Young Rebecca C., Welcker Jorg, Barger Christopher P., Hatch Scott A., Merkling Thomas, Kitaiskaia Evgenia V., Haussmann Mark F., Kitaysky Alexander S. (2017). Effects of developmental conditions on growth, stress and telomeres in black‐legged kittiwake chicks (Vol. 26).
Abstract: Early‐life conditions can drive ageing patterns and life history strategies throughout the lifespan. Certain social, genetic and nutritional developmental conditions are more likely to produce high‐quality offspring: those with good likelihood of recruitment and productivity. Here, we call such conditions “favoured states” and explore their relationship with physiological variables during development in a long‐lived seabird, the black‐legged kittiwake (Rissa tridactyla). Two favoured states were experimentally generated by manipulation of food availability and brood size, while hatching order and sex were also explored as naturally generating favoured states. Thus, the favoured states we explored were high food availability, lower levels of sibling competition, hatching first and male sex. We tested the effects of favoured developmental conditions on growth, stress, telomere length (a molecular marker associated with lifespan) and nestling survival. Generation of favoured states through manipulation of both the nutritional and social environments furthered our understanding of their relative contributions to development and phenotype: increased food availability led to larger body size, reduced stress and higher antioxidant status, while lower sibling competition (social environment) led to lower telomere loss and longer telomere lengths in fledglings. Telomere length predicted nestling survival, and wing growth was also positively correlated with telomere length, supporting the idea that telomeres may indicate individual quality, mediated by favoured states.
Keywords: antioxidant corticosterone early‐life conditions growth rate telomeres thrifty phenotype
Programme: 1162
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Duron Olivier, Binetruy Florian, Noël Valérie, Cremaschi Julie, McCoy Karen D., Arnathau Céline, Plantard Olivier, Goolsby John, Pérez de León Adalberto A., Heylen Dieter J. A., Van Oosten A. Raoul, Gottlieb Yuval, Baneth Gad, Guglielmone Alberto A., Estrada‐Peña Agustin, Opara Maxwell N., Zenner Lionel, Vavre Fabrice, Chevillon Christine. (2017). Evolutionary changes in symbiont community structure in ticks (Vol. 26).
Abstract: Abstract Ecological specialization to restricted diet niches is driven by obligate, and often maternally inherited, symbionts in many arthropod lineages. These heritable symbionts typically form evolutionarily stable associations with arthropods that can last for millions of years. Ticks were recently found to harbour such an obligate symbiont, Coxiella?LE, that synthesizes B vitamins and cofactors not obtained in sufficient quantities from blood diet. In this study, the examination of 81 tick species shows that some Coxiella?LE symbioses are evolutionarily stable with an ancient acquisition followed by codiversification as observed in ticks belonging to the Rhipicephalus genus. However, many other Coxiella?LE symbioses are characterized by low evolutionary stability with frequent host shifts and extinction events. Further examination revealed the presence of nine other genera of maternally inherited bacteria in ticks. Although these nine symbionts were primarily thought to be facultative, their distribution among tick species rather suggests that at least four may have independently replaced Coxiella?LE and likely represent alternative obligate symbionts. Phylogenetic evidence otherwise indicates that cocladogenesis is globally rare in these symbioses as most originate via horizontal transfer of an existing symbiont between unrelated tick species. As a result, the structure of these symbiont communities is not fixed and stable across the tick phylogeny. Most importantly, the symbiont communities commonly reach high levels of diversity with up to six unrelated maternally inherited bacteria coexisting within host species. We further conjecture that interactions among coexisting symbionts are pivotal drivers of community structure both among and within tick species.
Keywords: co‐evolution heritable symbiont communities maternally inherited bacteria symbiosis tick
Programme: 333
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David Grémillet, Aurore Ponchon, Michelle Paleczny, Maria-Lourdes D. Palomares, Vasiliki Karpouzi, Daniel Pauly. (2018). Persisting Worldwide Seabird-Fishery Competition Despite Seabird Community Decline (Vol. 28).
Keywords: catch reconstructions energetics food competition global fisheries marine management ocean conservation overfishing Sea Around Us seabird community Threatened species
Programme: 388
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K. Collomp, C. Buisson, F. Lasne, R. Collomp. (2015). DHEA, physical exercise and doping (Vol. 145).
Abstract: The dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEA-S) concentrations during acute and chronic exercise (training) have been investigated only fairly recently. DHEA is generally preferred to DHEA-S for exploring the acute exercise repercussions in laboratory or field tests because of its shorter elimination half-life. Conversely, DHEA-S is preferred to estimate chronic adaptations. Both can be measured noninvasively in saliva, and it is therefore possible to follow these hormone responses in elite athletes during competitive events and in healthy and pathological populations, without imposing additional stress. Indeed, the correlation between saliva and serum concentrations is high for steroid hormones, both at rest and during exercise. In this review, we will first summarize the current knowledge on the DHEA/DHEA-S responses to exercise and examine the potential modulating factors: exercise intensity, gender, age, and training. We will then discuss the ergogenic effects that athletes expect from the exogenous administration of DHEA and the antidoping methods of analysis currently used to detect this abuse.
Keywords: Acute physical exercise Antidoping analysis Chronic physical exercise Ergogenic effects
Programme: 1199
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Najat Bhiry, Armelle Decaulne, Myosotis Bourgon-Desroches. (2019). Development of a subarctic peatland linked to slope dynamics at Lac Wiyâshâkimî (Nunavik, Canada) (Vol. 29).
Abstract: A palaeoecological study of a subarctic minerotrophic peatland was undertaken to reconstruct the formation of the site as an archive of slope geomorphological processes. The study peatland is located about 400 m from Caribou slope (unofficial name) on Lepage Island, Lac Wiyâshâkimî, Nunavik (northern Québec, Canada). The site is close to the lakeshore and receives runoff directly from Caribou slope and its catchment. Gravity processes have been active on Caribou slope since the deglaciation of the region at approximately 6000 cal. yr BP. These processes may be differentiated in terms of Holocene stages of intensity. The objective of our study was to detect evidence of gravity processes in the peatland and to note their frequency since its establishment using loss-on-ignition testing, macrofossil analysis and radiocarbon dating. Our results indicate that peat began to accumulate over the sandy-gravelly sediments at around 4900 cal. yr BP. Larix Laricina, Carex aquatilis and Carex rostrata were present at this time until 4660 cal. yr BP, at which point these taxa were replaced by aquatic taxa such as Hippuris vulgaris and Daphnia (aquatic invertebrates). The percentage of mineral sediments (sand) remained high during this period, which could be linked to slope activity. After 4660 cal. yr BP, sandy sediments diminished while episodes of aquatic conditions and sand inflow occurred on at least three occasions (at 4660, 3905 and 3130 cal. yr BP). The increase in water flow and the introduction of more medium to fine sand into the peatland could be linked to slope movements and the long-distance runout of debris flow that we observed in the field. Given these factors, conditions at the study site remained wet from the earliest phases until the present. Unlike the subarctic permafrost peatlands in northern Québec, permafrost did not become established at the study site.
Programme: 1148
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Andrea Berbellini, Martin Schimmel, Ana MG Ferreira, Andrea Morelli. (2018). Constraining S-wave velocity using Rayleigh wave ellipticity from polarization analysis of seismic noise (Vol. 216). Bachelor's thesis, , .
Abstract: SUMMARY. We develop a new method for measuring ellipticity of Rayleigh waves from ambient noise records by degree-of-polarization (DOP) analysis. The new method, named DOP-E, shows a good capability to retrieve accurate ellipticity curves separated from incoherent noise. In order to validate the method we perform synthetic tests simulating noise in a 1-D earth model. We also perform measurements on real data from Antarctica and Northern Italy. Observed curves show a good fit with measurements from earthquake records and with theoretical ellipticity curves. The inversion of real data measurements for vS structure shows a good agreement with previous models. In particular, the shear-wave structure beneath Concordia station shows no evidence of a significant layer of liquid water at the base of the ice. The new method can be used to measure ellipticity at high frequency and therefore it will allow the imaging of near-surface structure, and possibly of temporal changes in subsurface properties. It promises to be useful to study near-surface processes in a wide range of geological settings, such as volcanoes, fault zones and glaciers.
Programme: 133
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Karen E. Godfrey, Colleen A. Dalton, Zhitu Ma, Vala Hjörleifsdóttir, Göran Ekström. (2019). A comparison of approaches for the prediction and inversion of surface wave phase delays (Vol. 217).
Abstract: SUMMARY. A controlled experiment was performed to investigate the influence of different assumptions made about the propagation of surface waves in surface wav
Programme: 133
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L. Gualtieri, E. Stutzmann, C. Juretzek, C. Hadziioannou, F. Ardhuin. (2019). Global scale analysis and modelling of primary microseisms (Vol. 218). Bachelor's thesis, , .
Abstract: Primary microseism is the less studied seismic background vibration of the Earth. Evidence points to sources caused by ocean gravity waves coupling with the seafloor topography. As a result, these sources should be in water depth smaller than the wavelength of ocean waves. Using a state-of-the-art ocean wave model, we carry out the first global-scale seismic modelling of the vertical-component power spectral density of primary microseisms. Our modelling allows us to infer that the observed weak seasonality of primary microseisms in the southern hemisphere corresponds to a weak local seasonality of the sources. Moreover, a systematic analysis of the source regions that mostly contribute to each station reveals that stations on both the east and west sides of the North Atlantic Ocean are sensitive to frequency-dependent source regions. At low frequency (i.e. 0.05 Hz), the dominant source regions can be located thousands of kilometres away from the stations. This observation suggests that identifying the source regions of primary microseisms at the closest coasts can be misleading.
Programme: 133
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M. Frietsch, A. M. G. Ferreira, G. J. Funning, J. Weston. (2019). Multiple fault modelling combining seismic and geodetic data: the importance of simultaneous subevent inversions (Vol. 218).
Abstract: SUMMARY. We present a new inversion method for modelling multiple fault sources combining seismic and geodetic data. The technique takes into account 3-D earth
Programme: 133
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