HAL Portal UPF (Université de la Polynésie française)
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Comparative transcriptomics identifies genes underlying growth performance of the Pacific black-lipped pearl oyster Pinctada margaritifera
No full textInternational audienceBackground: In bivalves, the rate at which organisms grow is a major functional trait underlying many aspects of their commercial production. Growth is a highly polygenic trait, which is typically regulated by many genes with small to moderate effects. Due to its complexity, growth variability in such shellfish remains poorly understood. In this study, we aimed to investigate differential gene expression among spat of the pearl oyster Pinctada margaritifera with distinct growth phenotypes.Results: We selected two groups of P. margaritifera spat belonging to the same F2 cohort based on their growth performance at 5.5 months old. Transcriptome profile analysis identified a total of 394 differentially expressed genes between these Fast-growing (F) and Slow-growing (S) phenotypes. According to functional enrichment analysis, S oysters overexpressed genes associated with stress-pathways and regulation of innate immune responses. In contrast, F oysters up-regulated genes associated with cytoskeleton activity, cell proliferation, and apoptosis. Analysis of genome polymorphism identified 16 single nucleotide polymorphisms (SNPs) significantly associated with the growth phenotypes. SNP effect categorization revealed one SNP identified for high effect and annotated for a stop codon gained mutation. Interestingly, this SNP is located within a gene annotated for scavenger receptor class F member 1 (SRF1), which is known to modulate apoptosis. Our analyses also revealed that all F oysters showed up-regulation for this gene and were homozygous for the stop-codon mutation. Conversely, S oysters had a heterozygous genotype and a reduced expression of this gene.Conclusions: Altogether, our findings suggest that differences in growth among the same oyster cohort may be explained by contrasted metabolic allocation between regulatory pathways for growth and the immune system. This study provides a valuable contribution towards our understanding of the molecular components associated with growth performance in the pearl oyster P. margaritifera and bivalves in general
The evolution of colour polymorphism in the sea snake Emydocephalus annulatus
No full textInternational audienceThe existence of distinct colour morphs within a single population is puzzling from an evolutionary perspective, because we would expect a morph that confers higher fitness to replace any others. Inshore populations of turtle-headed sea snakes (Emydocephalus annulatus) contain many melanic individuals, whereas banded patterns dominate most of the species’ range. We show that melanism may enhance fitness in polluted sites because darker skin both concentrates pollutants, and induces more frequent sloughing. The long-term stability in frequencies of melanic versus banded morphs in our study populations may reflect frequency-dependent fitness advantages driven by mimicry of sympatric and more toxic sea snakes. Consistent with that hypothesis, predatory fish were more likely to attack snake-shaped lures that were black rather than lures that were black-and-white banded. Overall, our data highlight the advantages of novel systems, such as sea snakes, for research on classic questions in evolutionary ecology
Mesophotic zone as refuge: acclimation and in-depth proteomic response of yellow gorgonians in the Mediterranean sea
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L’agriculture tropicale en milieu insulaire, entre tradition et innovation. Vers une autosuffisance des productions vivrières en Polynésie française: Enquêtes dans les différents archipels : Nuku Hiva aux Marquises, Rangiroa aux Tuamotu-Gambier, Rurutu aux Australes, Taha’a, Moorea et Tahiti dans celui de la Société
No full textInternational audienceIn Französisch-Polynesien verbirgt sich hinter dem epinal anmutenden Bild von weißen Sandstränden, die von türkisfarbenem Wasser und Kokospalmen gesäumt sind, eine kulturelle, soziale und wirtschaftliche Aktivität von größter Notwendigkeit: die Landwirtschaft, die zwischen Tradition und Innovation angesiedelt ist. Dieses Buch gibt einen Überblick über die Nahrungsmittelproduktion und beantwortet zahlreiche Fragen zu den Formen der Landwirtschaft, die in diesem archipelagischen Gebiet praktiziert werden, das weit von der Metropole entfernt, unbekannt und doch so groß wie Westeuropa ist. Auf welche Weise ist die polynesische Landwirtschaft organisiert und funktioniert sie? Welche landwirtschaftlichen Tätigkeiten werden innerhalb der Archipele ausgeübt? Welche Vorschriften gelten für sie? Welche Maßnahmen zur Entwicklung des ländlichen Raums und welche Synergien werden in diesen Gebieten gefördert? Die Antworten auf diese und ähnliche Fragen basieren auf einer umfassenden Literaturstudie, Feldstudien und der Auswertung von Interviews mit Akteuren. Die Monographien der untersuchten Inseln und Atolle zeugen von der Vielfalt der landwirtschaftlichen Aktivitäten und Produktionen: von Kopra bis Monoi, von der Viehzucht bis zur Agroindustrie, von Zuckerrohr bis Rum, nicht zu vergessen die Fischerei, die Perlenzucht, den Obstbau, die Forstwirtschaft, den Weinbau, das Handwerk, den Gartenbau und die Heilpflanzenproduktion. Die Studie zeigt die Vielfalt der landwirtschaftlichen und ländlichen Praktiken, der Ressourcen, der Errungenschaften und der laufenden und künftigen Projekte.In French Polynesia, behind the epinal image of white sandy beaches, bordered by turquoise waters and coconut palms, lies a cultural, social and economic activity of the utmost necessity: agriculture, which lies between tradition and innovation. This book provides an overview of food production and answers many questions about the forms of agriculture practised in this archipelagic territory, far from the mainland, little-known and yet as vast as Western Europe. How is Polynesian agriculture organised and operates? What agricultural activities are carried out in the archipelagos? What regulations apply? What is being done to promote rural development, and what synergies are being created in these areas? The answers to these questions and their corollaries are based on an exhaustive literature review, field surveys and analysis of interviews with stakeholders. The monographs on the islands and atolls studied show the diversity of agricultural activities and production: from copra to monoi, from livestock farming to agro-industry, from sugar cane to rum, not forgetting fishing, pearl farming, arboriculture, forestry, viticulture, crafts, horticulture and medicinal plants. The study shows the diversity of agricultural and rural practices, resources, achievements and current and future projects.En Polynésie française, derrière l’image d’Epinal de plages de sable blanc, bordées d’eaux turquoise, de cocotiers, se cache une activité culturelle, sociale, économique, de première nécessité : l’agriculture qui se situe entre tradition et innovation. Cet ouvrage dresse un état des productions vivrières et répond à de nombreuses questions sur les formes d’agriculture pratiquées dans ce territoire archipélagique, éloigné de la métropole, méconnu et pourtant aussi vaste que l’Europe occidentale. De quelle façon s’organise et fonctionne l’agriculture polynésienne ? Quelles sont les activités agricoles exercées au sein des archipels ? Quelle réglementation s’y applique ? Quelles sont les actions en faveur du développement rural, et les synergies insufflées dans ces territoires ? Les réponses à ces questions et leur corollaire s’appuient sur une étude bibliographique exhaustive, sur des enquêtes de terrain, et l’analyse d’entretiens auprès d’acteurs. Les monographies des îles et atolls étudiés témoignent de la diversité des activités et productions agricoles : du coprah au monoï, de l’élevage à l’agro-industrie, de la canne à sucre au rhum, sans oublier la pêche, la perliculture, l’arboriculture, la sylviculture, la viticulture, l’artisanat, l’horticulture et les plantes médicinales. L’étude montre la diversité des pratiques agricoles et rurales, des ressources, des réalisations, et des projets en cours et à venir
Dominant contribution of atmospheric nonlinearities to ENSO asymmetry and extreme El Niño events
No full textInternational audienceAbstract Extreme El Niño events have outsized impacts and strongly contribute to the El Niño Southern Oscillation (ENSO) warm/cold phase asymmetries. There is currently no consensus on the respective importance of oceanic and atmospheric nonlinearities for those asymmetries. Here, we use atmospheric and oceanic general circulation models that reproduce ENSO asymmetries well to quantify the atmospheric nonlinearities contribution. The linear and nonlinear components of the wind stress response to Sea Surface Temperature (SST) anomalies are isolated using ensemble atmospheric experiments, and used to force oceanic experiments. The wind stress-SST nonlinearity is dominated by the deep atmospheric convective response to SST. This wind-stress nonlinearity contributes to ~ 40% of the peak amplitude of extreme El Niño events and ~ 55% of the prolonged eastern Pacific warming they generate until the following summer. This large contribution arises because nonlinearities consistently drive equatorial westerly anomalies, while the larger linear component is made less efficient by easterly anomalies in the western Pacific during fall and winter. Overall, wind-stress nonlinearities fully account for the eastern Pacific positive ENSO skewness. Our findings underscore the pivotal role of atmospheric nonlinearities in shaping extreme El Niño events and, more generally, ENSO asymmetry
The emergence of Free France in the South Pacific (June 1940 – October 1941): Sociability circles and political turmoil in a colonial context
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The Hybrid Recharge Delayed Oscillator: A More Realistic El Niño Conceptual Model
No full textInternational audienceAbstract El Niño–Southern Oscillation (ENSO) is the leading mode of climate interannual variability, with large socioeconomical and environmental impacts, potentially increasing with climate change. Improving its understanding may shed further light on its predictability. Here we revisit the two main conceptual models for explaining ENSO cyclic nature, namely, the recharge oscillator (RO) and the advective–reflective delayed oscillator (DO). Some previous studies have argued that these two models capture similar physical processes. Yet, we show here that they actually capture two distinct roles of ocean wave dynamics in ENSO’s temperature tendency equation, using observations, reanalyses, and Climate Model Intercomparison Project (CMIP) models. The slow recharge/discharge process mostly influences central-eastern Pacific by favoring warmer equatorial undercurrent and equatorial upwelling, while the 6-month delayed advective–reflective feedback process dominates in the western-central Pacific. We thus propose a hybrid recharge delayed oscillator (RDO) that combines these two distinct processes into one conceptual model, more realistic than the RO or DO alone. The RDO eigenvalues (frequency and growth rate) are highly sensitive to the relative strengths of the recharge/discharge and delayed negative feedbacks, which have distinct dependencies to mean state. Combining these two feedbacks explains most of ENSO frequency diversity among models. Thanks to the two different spatial patterns involved, the RDO can even capture ENSO spatiotemporal diversity and complexity. We also develop a fully nonlinear and seasonal RDO, even more robust and realistic, investigating each nonlinear term. The great RDO sensitivity may explain the observed and simulated richness in ENSO’s characteristics and predictability. Significance Statement El Niño and La Niña events, and the related Southern Oscillation, cause the largest year-to-year variations of Earth’s climate. Yet the theories behind them are still debated, with two main conceptual models being the recharge oscillator and the delayed oscillator. Our purpose here is to address this debate by developing a more realistic theory, a hybrid recharge delayed oscillator. We show how simple yet realistic it is, with equivalent contributions from the slow recharge process and from the faster delayed feedback. It even captures the observed El Niño and La Niña diversity in space and in frequency. Future studies could use the simple theoretical framework provided here to investigate El Niño–Southern Oscillation (ENSO) in observations, theories, climate models diagnostics and forecasts, and global warming projections
An Information Theoretic Metric for Measurement Vulnerability to Data Integrity Attacks on Smart Grids
No full textInternational audienceA novel metric that describes the vulnerability of the measurements in power systems to data integrity attacks is proposed. The new metric, coined vulnerability index (VuIx), leverages information theoretic measures to assess the attack effect in terms of the fundamental limits of the disruption and detection tradeoff. The result of computing the VuIx of the measurements in the system yields an ordering of their vulnerability based on the degree of exposure to data integrity attacks. This new framework is used to assess the measurement vulnerability of IEEE 9-bus and 30-bus test systems and it is observed that power injection measurements are significantly more vulnerable to data integrity attacks than power flow measurements. A detailed numerical evaluation of the VuIx values for IEEE test systems is provided
