Les écosystèmes sub-Antarctiques sont particulièrement vulnérables aux perturbations environnementales et notamment aux invasions biologiques. L'introduction du Chat (Felis silvestris catus) sur la Grande Terre de l'archipel des Kerguelen a eu des effets désastreux sur les communautés d'oiseaux marins. Ce prédateur doit sa survie dans cet environnement à la présence d'une proie introduite, le Lapin (Oryctolagus cuniculus), qui constitue sa ressource principale pendant l'hiver lorsque les oiseaux marins sont repartis en mer. L'éradication du chat n'apparaît pas être une solution réaliste compte tenu de la taille de l'île (6675 km2) et son inaccessibilité. De plus elle serait susceptible de conduire à des résultats non souhaités comme par exemple une explosion démographique des populations de lapins. La mise en place d'une politique de gestion adaptée nécessite d'améliorer notre connaissance des facteurs qui conditionnent la dynamique spatio-temporelle des populations de chats. Au cours de cette thèse, j'ai cherché à identi_er les mécanismes des interactions entre le chat, le lapin et la végétation, car elles sont attendues conditionner celles existantes entre le chat et les oiseaux marins. J'ai analysé la dynamique spatio-temporelle de quatre populations de chats sur la Grande Terre et j'ai en particulier recherché si des conditions environnementales spatialement corrélées (effet Moran) pouvaient, en se propageant dans la chaine alimentaire, synchroniser les variations temporelles d'abondance des populations de chats. Enfin, j'ai étudié l'impact des variations spatio-temporelles d'abondance des populations de chats sur les variations spatio-temporelles de la structure génétique des populations de chats. / Sub-Antarctic ecosystems are particularly vulnerable to environmental perturbations including biological invasions. The introduction of the feral cat (Felis silvestris catus) on the Grande TerreIsland of the Kerguelen archipelago has lead to detrimental effects on seabird's communities. Cat survival in this environment is possible because of the presence of the introduced rabbit (Oryctolagus cuniculus), which constitute the main prey of the cat during winter when most seabirds are offshore. Cat eradication is not a realistic solution given the size and inaccessibility of the island (6675 km2). Moreover it can lead to unwanted results such as the demographic explosion of rabbit populations. The design of appropriate management policy needs to improve our understanding of the factors that influence the spatio-temporal dynamics of cat populations. In this thesis, I explored the mechanisms of cat-rabbit-vegetation interactions, as they are expected to determine interactions existing between cats and seabirds. I analyzed the spatio-temporal dynamics of four cat populations on Grande Terre Island and I especially sought whether environmental conditions spatially correlated (Moran effect) could synchronize cat through their effect on the trophic web pathways. Finally, I studied the impact of spatio-temporal

Tout semble avoir été dit sur Mayotte, les Comores et la France, or le statut juridique de ce territoire n'a pas encore livré tous ses secrets, ni épuisé tous ses effets. La problématique générale de cette thèse consiste à savoir comment ce statut juridique de Mayotte peut rendre compte de la double identité, de la double appartenance de cette île. La réponse à cette question générale se décline en deux aspects très complémentaires : 1) Peut-on penser Mayotte abritée du droit international ? La réponse à cette question est négative ; 2) Peut-on penser Mayotte uniquement par référence au droit de l'État français ? Là aussi, la réponse est négative. La thèse défendue s'illustre comme suit : elle préconise la vocation internationale du statut de Mayotte et la vocation franco-comorienne de celui-ci. La vocation internationale du statut de Mayotte part de l'idée qu'il faut, aujourd'hui, dépasser le statu quo qui préside au différend territorial entre la France et les Comores. Ce statu quo est l'expression d'un antagonisme et d'un « silence » sur les rapports entre droit interne et droit international. Ce « silence » montre une opposition entre les Comores pro-internationalistes et la France, pro-interniste. Aucun dialogue ne s'ensuit. Les solutions du droit international sont au nombre de deux : une solution stricte, par application du principe de l'uti possidetis juris, soit le rattachement du territoire de Mayotte aux Comores. Une seconde solution très innovante consisterait en l'exercice d'une co-souveraineté franco-comorienne sur Mayotte. En l'état des forces politiques, les solutions du droit international paraissent délicates à mettre en oeuvre. Aussi la thèse du maintien de Mayotte française semble devoir l'emporter, mais dans une perspective modernisée. Voilà quelle pourrait être l'issue du dialogue droit interne et droit international. La vocation franco-comorienne de Mayotte signifie que le maintien de Mayotte française doit se penser en termes de double appartenance. Le renoncement, accepté par l'État comorien, devra être accompagné d'une coopération internationale bilatérale forte. C'est pourquoi le statut mahorais doit se penser en termes de double identité. Dans ces conditions, un dialogue véritable entre l'État français et l'État Comorien sur Mayotte française serait établi. On peut penser ce dialogue durable car il ne tend à donner une satisfaction exclusive ni à l'un ou ni à l'autre des protagonistes. Autant le dialogue droit interne et droit international favorise les intérêts de l'État français ; autant le dialogue qui s'ensuit doit satisfaire les deux parties. Ainsi, afin de répondre aux interrogations soulevées par notre problématique et pour mieux les appréhender, notre étude est divisée en deux parties. La première est consacrée à la vocation internationale du statut de Mayotte. La deuxième partie présente la vocation franco-comorienne du statut de cette île. / The case of Mayotte has been extensively studied. However unresolved issues regarding the legal status of the territory persist, owing to Mayotte belonging to both the Comoros and France. This study examines how the legal status of Mayotte can reflect its double identity. To answer this question, it is necessary to envision two complementary aspects of the problem: is Mayotte immune from international law? The answer is no; does Mayotte fall exclusively under French law? Again, the answer is no. This thesis reveals the opportunity for Mayotte to define itself both as an international and as a French Comorian territory. Embracing its international vocation, Mayotte would move beyond the statu quo that stems from the territorial dispute between France and the Comoros. The current situation is the symptom of an antagonism between international and domestic law which explains the absence of discussion over the case of Mayotte. The Comoros promotes international law whereas France is in favour of internal law. There are two main international law solutions: a strict one, by the application of the principle of “uti possidetis juris”, in other words the unification of Mayotte territory with Comoros. The second solution is an innovative one which would consist in a French-Comorian shared sovereignty concerning Mayotte. Considering political forces, it does not seem easy to implement international law solutions. Also, in a modernized perspective, the thesis of maintaining a French Mayotte island is to be promoted. This could eventually be the solution of internal law and international law. French-Comorian purpose about Mayotte means that the maintaining of a French Mayotte island should be thought in terms of a double belonging. The renunciation, accepted by the Comorian state, should have to be associated with a strong bilateral international cooperation. That is why the status of Mayotte also has to be thought in terms of a double identity. In these conditions, a real dialogue can be established between France and the Comoros about a French Mayotte. Thus, long-standing talks are possible because none of the protagonists will be given exclusive satisfaction. Even though the internal law and international law dialogue encourages French interests, the dialogue which follows has to satisfy both parties. Thus, to answer the questions raised by our problematic, we have divided our study into two parts, the first one is devoted to the international purpose of Mayotte’s status and the second one deals with its French-Comorian purpose.

Syfte: Syftet med studien är att undersöka vilka faktorer och åtgärder som kan vara framgångsrika för säsongsförlängning hos verksamheter i skärgårdsmiljö. Metod: En kvalitativ metodansats har tillämpats genom sju intervjuer. Komplettering har gjorts med hjälp av sekundärdata.  Teoretisk referensram: Den teoretiska referensramen utgår från Conceptual approaches to seasonality causationav Goulding (2006) samt Influences on patterns of tourism seasonalityav Butler (2001). Empiri: Empirin består av fyra öppna intervjuer och tre halvstrukturerade intervjuer som genomförts med representanter från logiverksamheter i skärgården. För att komplettera materialet presenteras de berörda öarnas utbud och tillgänglighet i tabeller. Slutsatser: Verksamheter i Stockholm skärgård är beroende av naturliga och institutionella faktorer såsom väderlek, högtider och resvanor. De är främst attraktiva för besökare under sommarhalvåret och verksamheter upplever en dramatisk minskning av antalet besökare under lågsäsongen. Utbudet som finns är begränsat till sommarsäsongen då flera aktiviteter innebär utevistelse. Dock visar en del verksamheter på att de försöker hitta andra attraktioner under lågsäsong än under högsäsong för att hålla uppe besöksantalet. De handlingar som verksamheterna utför fokuserar främst på att öka tillväxten under sommarsäsong och de arbetar inte aktivt med att förlänga säsongen. Resultat visar på att de största begränsningarna som verksamheter i Stockholms skärgård har är personalbrist, naturliga orsaker samt transportmöjligheter. Det leder till att majoriteten av verksamheterna satsar på att utöka antalet besökare under högsäsongen, vilket i sin tur kan leda till problematik i bärkraften. / Purpose: The purpose of this study is to investigate and analyze actions which businesses in archipelago environments may use to successfully extend the season. Method: A qualitative research method approach has been applied through seven interviews. Completion has been made using secondary data. Theoretical framework: The theoretical framework is based on Conceptual approaches to seasonality causation from Goulding (2006) and Influences on patterns of tourism seasonalityby Butler (2001). Empericism: The empericism consists of four open interviews and three semistructured interviews conducted with representatives from different lodging businesses in the archipelago. Charts consisting information about the referred islands complete the interviews.  Conclusions: Businesses in Stockholm archipelago are dependent on natural and institutional factors such as weather, bank holidays and travel habits. Stockholm archipelago is especially attractive to visitors during the summer. Lodging businesses therefore experience a dramatic reduction in the number of visitors during the off-season. The available range is limited to the summer season when several activities are dependant on weather conditions, but some businesses show that they try to find other attractions during the low season to keep up with the declining number of visitors. The actions that the businesses take is mainly focused on increasing growth during the summer season and they are  generally not actively working to extend the seasons. Results show that the greatest limitations that the businesses face in Stockholm archipelago are staff shortages, natural causes and public transport limitations. That is, the extension of seasons being limited as the businesses mainly invest in the summer season, which in turn may lead to sustainability issues.

Au travers d’une monographie des sites archéologiques d’Acoua, village de parler kibushi kimaore situé au nord-ouest de Grande Terre, cette recherche propose d’étudier la période des XIIe-XVIe siècles à Mayotte. Cette période est caractérisée par d’importants changements culturels, religieux et politiques conduisant à l’instauration progressive d’une société stratifiée et islamisée. Il sera notamment question, au travers des thématiques explorées par notre étude archéologique (pratiques funéraires, évolutions de la culture matérielle, intégration dans les réseaux marchands de l’océan Indien), de déterminer les filiations et processus culturels qui ont contribué à façonner la société ancienne de Mayotte, île dont le peuplement complexe, caractéristique des cultures dites « de franges », selon l’expression popularisée dans cette partie du monde par Paul Ottino, est située à la rencontre de grandes aires culturelles : monde africain bantou, monde malgache et monde arabo-persan, hissant cette île de l’archipel comorien au rang de véritable interface culturelle, commerciale et migratoire entre l’Afrique et Madagascar, « plaque tournante et microcosme de l’océan Indien » pour reprendre l’expression de Claude Allibert. / Through this monograph of Acoua’s archaeological sites - a Kibushi kimaore speaking village located in the northwest of Grande Terre - this research proposes to study the XIIth-XVIth centuries period, in Mayotte. This period is characterized by important cultural, religious and political changes leading to the gradual establishment of a stratified and Islamized society. It will be question here, through the themes explored by our archaeological study (funerary practices, evolutions of material culture, integration in the Indian Ocean trading networks), to determine the cultural affiliations and processes that have contributed to shaping Mayotte’s ancient society, an island whose complex settlement, characteristic of cultures known as "fringes" - according to the expression popularized in this part of the world by Ottino - is located at the meeting of meany great cultural areas: African Bantou world, Malagasy world and Arab-Persian world, hoisting this island of the Comorian archipelago to the rank of true cultural, commercial and migratory interface between Africa and Madagascar : a "hub and microcosm of the Indian Ocean", to use the expression of Claude Allibert.

Algumas ilhas oceânicas como o Arquipélago de São Pedro e São Paulo podem ser consideradas áreas remotas e preservadas devido a sua distância do continente. Entretanto, essas regiões não estão isentas da influência de agentes antrópicos oriundos das regiões costeiras, como é o caso dos poluentes orgânicos persistentes (POPs). A presente proposta visou determinar a ocorrência e distribuição de POPs na biota marinha, do Arquipélago de São Pedro e São Paulo. As extrações das amostras foram realizadas em micro-ondas e os pesticidas organoclorados e os PCBs/PBDEs foram analisados respectivamente por cromatografia a gás com detecção por captura de elétrons e espectrometria de massas. Os compostos predominantes foram os PCBs e os DDTs que apresentaram, respectivamente, as concentrações máximas de: 127,7 e 34,37 ng g-1 para Exocoetus volitans (Peixe-voador), 98,15 e 8,89 ng g-1 para Sula leucogaster (Atobá-marrom) e 90,5 e 18,86 ng g-1 Grapsus grapsus (Aratu). Os baixos valores dos contaminantes sugerem um relativo grau de isolamento e preservação, porém a ocorrência e o perfil de distribuição dos PCBs sustenta a hipótese de que a principal fonte de contaminação em áreas remotas é o transporte atmosférico de longa distância, e demonstra a ubiquidade desses poluentes no ambiente marinho. / Some oceanic islands, such as São Pedro e São Paulo Archipelago may be considered remote areas and preserved due to its distance from the mainland. However, these areas are not exempt from the influence of anthropogenic agents from coastal regions, such as persistent organic pollutants (POPs). This proposal aimed to determine the occurrence and distribution of POPs in marine biota of São Pedro e São Paulo Archipelago. Samples extractions were performed with microwave and organochlorine pesticides and PCBs/PBDES was respectively analysed by gas chromatography with electron capture detection and mass spectrometry. The predominant compounds were PCBs and DDTs that presented, respectively, the maximum concentrations 127.7 and 34.37 ng g-1 to Exocoetus volitans (Flying fish), 98.15 and 8.89 ng g-1 to Sula leucogaster (Brown Booby) and 90.5 and 18.86 ng g-1 to Grapsus grapsus (Sally Lightfoot crab). The low levels of contaminants suggest a relative degree of isolation and preservation, but the occurrence and distribution profiles of PCBs supports the hypothesis that the main source of contamination in remote areas is long range atmospheric transport, and demonstrates the ubiquity of those pollutants in the marine environment.

No description available.

The evolutionary conserved insulin and nutrient signaling network regulates growth andmetabolism. Nutrients are directly utilized for growth or stored, mostly as triglycerides. InDrosophila, activation of insulin/nutrient signaling in the fat body (the fly equivalent of liverand adipose tissue), causes an increase in fat stores composed of several small-size lipiddroplets (LDs). Conversely, fasting produces an increase in LD size and a decrease in fatcontents. The TOR kinase and its substrate S6 kinase (S6K) play a central role in this response,and particularly in Drosophila, they have been shown to orchestrate cell-autonomous andhormone-controlled growth. However, despite extensive research studies on different modelorganisms (mouse, fly, worm) to decipher the molecular and physiological functions of S6K,nothing is known about how its degradation is regulated.Taking advantage of the inducible RNA interfering (RNAi) library from NIG (Japan), we haveperformed three genetic screens to identify novel regulators of steroidogenesis, lipidmetabolism and dS6K-dependent growth. First, RNAi lines were screened in the ring gland; anorgan that controls the progression of the developmental steps by producing the steroidhormone ecdysone. Out of 7,000 genes screened, 620 positive candidates were identified toproduce developmental arrest and/or overgrowth phenotypes. Then, we challenged 4,000 genesby RNAi screening able to recapitulate the larger sized LD phenotype as obtained uponstarvation, leading to the identification of 24 potential candidates. Finally, the RNAi lines werescreened for their ability to enhance a growth phenotype dependent of the Drosophila S6K(dS6K). Out of 7,000 genes screened, 45 genes were identified as potential negative regulatorsof dS6K. These genes were further used to design a novel protein-protein interaction networkcentered on dS6K through the available data from yeast-2-hybrid (Y2H) assay. The most potentinteractors were then analyzed by treatment of cultured S2 cells with the corresponding doublestrand RNA (dRNA). Western blotting thus, allowed us to discriminate between the geneproducts that regulate dS6K levels versus those that regulate its phosphorylation, as a hallmarkfor its kinase activity. Interestingly, archipelago (ago), which encodes a component of an SCFubiquitinligase known to regulate the degradation of dMyc, Cyclin E and Notch, was identifiedas a negative regulator of dS6K-dependent growth. Based on the Y2H available data showingthat Ago and dS6K interact each other and the presence of a putative Ago-interaction motif indS6K, we hypothesized that Ago causes an ubiquitin-mediated degradation of dS6K. Ourmolecular data showed that loss of ago caused an elevated level of dS6K, which confirms arole of Ago in controlling dS6K degradation. Altogether our findings emphasize the importanceof the saturating screening strategies in Drosophila to identify novel regulators of metabolicand signaling pathways.

About 6% of all angiosperms are dioecious. This separation of sexual function to male and female individuals, and the fundamentally different patterns of reproductive resource allocation that follows that separation, are thought to have important ecological and evolutionary consequences for plant enemy interactions.  I have studied whether intersexual differences in susceptibility to natural enemies can be explained by intersexual differences in resource allocation. In cases when sexual dimorphic traits form the target resource of a particular enemy I expected the enemy to select the best resource. The study system is the perennial dioecious herb, Silene dioica (Caryophyllaceae) and three of its specialist natural enemies, two insect herbivores the fly Delia criniventris (Anthomyiidae) and the twirler moth Caryocolum viscariella (Gelechiidae) and one systemic anther smut fungus Microbotryum violaceum. All three share the same food recourse, the floral stems, of their host plant. I studied the interaction on nine islands in a rising Bothinan archipelago over seven consecutive years. Both herbivores attacked female plants more than male plants (D. criniventris, 32.8% females, 30.7% males; C. viscariella, 4% females, 2% males). This attack pattern was consistent over years and islands and also correlated with a number of sexually dimorphic traits suggesting that females offer the better resource. Herbivore attack had no effect on plant survival but a significant effect on re-flowering the following year. Non-attacked females had an estimated mean re-flowering rate of 30.2%, and non-attacked males of 31%. Herbivore-attacked females had an estimated re-flowering rate of 46% compared with 38.4% for males. Females showed a stronger compensatory response to attack and tended to re-flower more often than males. Attack rates differed markedly in the different stages of primary succession. They were consistently higher in the youngest zone and decreased in parallel to progressing succession. This zonal pattern of decreasing attack rates correlated with several plant attributes, a decrease in plant size and nitrogen content, and an increased content of secondary compounds, but not to host plant density. We failed to come up with a simple explanation for the spatial structure with chronic high attack rates in the younger zones. However, the consistent patterns in attack rate suggest that a suite of abiotic and biotic factors interact and reinforce the strength and direction of selection. In general females were more frequently diseased by the anther smut Microbotryum violaceum than males with two exceptions. Disease frequencies were male biased on islands with low disease levels and in one of the seven study years. The change in disease frequencies from male to female bias confirm earlier studies suggesting that the relative contribution of the two components of infection risk, disease encounter and per contact infection probability can vary with population disease level. The change in the proportions of diseased males and females that was observed in one of the study years, followed a year of extreme weather conditions (prolonged drought). Both sexes showed a similar decline in flowering but diseased females decreased more than diseased males. This difference in response can be explained if considering that disease is more resource demanding in females than in males. Except for resources needed for mycelial growth and spore production, in females resources are also needed to restructure their sex expression and produce anthers. My study shows (i) that in dioecious species traits that are sexually dimorphic are of great importance for understanding the outcome of interactions with natural enemies, (ii) that the strengths and directions of enemy-host plant interactions are strongly shaped by both biotic and abiotic conditions.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Algumas ilhas oceânicas como o Arquipélago de São Pedro e São Paulo podem ser consideradas áreas remotas e preservadas devido a sua distância do continente. Entretanto, essas regiões não estão isentas da influência de agentes antrópicos oriundos das regiões costeiras, como é o caso dos poluentes orgânicos persistentes (POPs). A presente proposta visou determinar a ocorrência e distribuição de POPs na biota marinha, do Arquipélago de São Pedro e São Paulo. As extrações das amostras foram realizadas em micro-ondas e os pesticidas organoclorados e os PCBs/PBDEs foram analisados respectivamente por cromatografia a gás com detecção por captura de elétrons e espectrometria de massas. Os compostos predominantes foram os PCBs e os DDTs que apresentaram, respectivamente, as concentrações máximas de: 127,7 e 34,37 ng g-1 para Exocoetus volitans (Peixe-voador), 98,15 e 8,89 ng g-1 para Sula leucogaster (Atobá-marrom) e 90,5 e 18,86 ng g-1 Grapsus grapsus (Aratu). Os baixos valores dos contaminantes sugerem um relativo grau de isolamento e preservação, porém a ocorrência e o perfil de distribuição dos PCBs sustenta a hipótese de que a principal fonte de contaminação em áreas remotas é o transporte atmosférico de longa distância, e demonstra a ubiquidade desses poluentes no ambiente marinho. / Some oceanic islands, such as São Pedro e São Paulo Archipelago may be considered remote areas and preserved due to its distance from the mainland. However, these areas are not exempt from the influence of anthropogenic agents from coastal regions, such as persistent organic pollutants (POPs). This proposal aimed to determine the occurrence and distribution of POPs in marine biota of São Pedro e São Paulo Archipelago. Samples extractions were performed with microwave and organochlorine pesticides and PCBs/PBDES was respectively analysed by gas chromatography with electron capture detection and mass spectrometry. The predominant compounds were PCBs and DDTs that presented, respectively, the maximum concentrations 127.7 and 34.37 ng g-1 to Exocoetus volitans (Flying fish), 98.15 and 8.89 ng g-1 to Sula leucogaster (Brown Booby) and 90.5 and 18.86 ng g-1 to Grapsus grapsus (Sally Lightfoot crab). The low levels of contaminants suggest a relative degree of isolation and preservation, but the occurrence and distribution profiles of PCBs supports the hypothesis that the main source of contamination in remote areas is long range atmospheric transport, and demonstrates the ubiquity of those pollutants in the marine environment.