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Inbreeding Avoidance Mechanism: How Premating Conditions May Influence the Mating System in a Quasi-Gregarious Parasitoid of Aphids, Aphidius Matricariae

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Inbreeding Avoidance Mechanism: How Premating Conditions May Influence the Mating System in a Quasi-Gregarious Parasitoid of Aphids, Aphidius Matricariae Inbreeding avoidance mechanism: how premating conditions may influence the mating system in a quasi-gregarious parasitoid of aphids, Aphidius matricariae. Bourdais Delphine President: Prof. Hans Van Dyck, UCL, ELI-B, Belgium Supervisor: Prof. Thierry Hance, UCL, ELI-B, Belgium Jury members: Prof. Joan van Baaren, Université de Rennes 1, France Prof. Jacques Brodeur, Université de Montreal, Canada Prof. Emmanuel Deshouant, Université Lyon 1, France Prof. Caroline Nieberding, UCL, ELI-B, Belgium 1 2 Remerciements La vie n’est faite que d’opportunités qu’il faut parfois savoir saisir au vol sans trop se poser de questions… Et aujourd’hui je peux avouer que la réalisation de cette thèse n’a pas échappé à cette règle qui m’est si chère. Mon entrée dans le monde merveilleux des parasitoïdes s’est faite en 2003 au cours d’un stage au labo d’Ecobiologie des Insectes Parasitoides de Rennes. Merci Anne-Marie, Denis, Liliane et les autres de m’avoir donné une si belle première vision d’un labo de recherche, alors que je n’étais encore qu’une jeune étudiante. Je n’ai pas pu continuer avec vous mais je me suis quand même incrustée encore 1 année pour mes manips de DEA, même si mon bureau officiel était dans une autre unité ;-) Merci Joan de m’avoir donné la chance de continuer à observer mes petites bestioles… Saisir sa chance au vol… C’est peut être comme ça que je me suis retrouvée en Belgique il y a maintenant presque 7 années… Merci Thierry de m’avoir accueillie et d’avoir cru en moi, même après mon échec au FRIA. Sans vous, rien de tout cela n’aurait été possible. Et puis finalement, un malheur s’est transformé en bonheur avec ce poste d’assistante et ce sujet de thèse toujours facile à expliquer aux non scientifiques : « ha, alors toi ton truc c’est d’étudier le sexe ! – euh…. C’est un peu ça oui… ». Ces 6 années à donner des TP n’auraient pas été si amusantes sans les collègues assistants et notamment l’équipe des Invertépotes. Val, Oksana, Elé, Jérôme, Arnaud, on s’est quand même bien marré lors des dissections et la migration de la moule restera une grande avancée scientifique ! Mr Remacle, Daniel, Willy, Thierry, Caroline et les autres Invertépotes, je n’oublierai pas de sitôt nos soupers écrevisses qui se finissaient on ne sait trop comment, et parce qu’il fallait bien assurer la dissection de 14h en expliquant avec beaucoup d’assurance que non, on ne savait pas pourquoi ça sentait la moule-frite dans la salle, et que non, ce n’était pas notre anniversaire quand les chanceux qui étaient encore autour de la table se ramenaient avec un gâteau en chantant. Merci pour tous ces moments… Et parce que j’ai eu la chance de faire partie du staff du stage de Bio Marine, un grand merci à Jérôme Mallefet et à toute l’équipe des stages de Wimereux pour avoir fait découvrir à la Bretonne que je suis le nom de (presque) toutes les bestioles que je croisais sur la plage étant petite. Et aussi parce que je me suis découverte une passion (culinaire j’entends) pour les algues ;-) Merci Delphine de m’avoir si gentillement ouvert la porte des dissections vêté, grâce à toi j’ai pu concrétiser un vieux souhait de cavalière biologiste. 3 Merci à tous les collègues du labo qui sont devenus des amis, parce que quand j’ai débarqué ici j’ai pu vérifier que l’hospitalité belge n’était pas une légende. Val, ma copine du bureau (et quel grand bureau !) parce que on a toujours réussi à ne pas se rentrer dedans avec nos chaises quand on se levait et que ça, c’est un miracle (tu te doutes bien qu’il y a beaucoup plus de choses pour lesquelles je dois te dire merci… demande à Simon il te le dira), Brigitte et Dominique les secrétaires et comptables de choc qui sont bien plus que cela dans la vie du labo, Isa pour les cafés au KafKaf et ton rire qui a égayé le labo durant toutes ces années, David pour m’avoir soulagée quelques mois : je n’étais alors pas la seule dans ce labo à parler sexe, mais aussi pour toute ton aide si précieuse durant cette rédaction (tu as bien essayé de me vexer avec tous tes commentaires mais non… loupé !), Chris le brameur fou, les acarineux : Sabrine, Gwendo, Guillaume, Anne- Cath (merci pour toutes tes relectures, même de dernière minute, ton aide en stat…), les « nouveaux » Fatou, Jennifer, Loulou, Aurore… et ceux qui ne sont déjà plus là mais que je n’oublie pas : Fred, Hervé et les Peasty’ Boys pour ne citer qu’eux. Merci Camille pour ton aide en stat (oui vous l’aurez compris, les stat c’est pas mon truc), Julie, l’autre Chris, Michel, Stéphane, Thomas, Marc (en souvenir de nos discussions des débuts à l’insectarium et de ton aide toujours bienvenue dans les phytotrons et les serres)… Un grand merci à Ellyn pour avoir corrigé en temps record mes nombreuses fôtes d’anglais, ca vaut bien quelques dessins d’acariens ;-) Et tous ceux qui ne sont pas cités ici mais qui ont égayé les midis, les week-end et les soupers de Nowel… la liste est longue ! Parceque il y autre chose dans la vie que la thèse et son labo (ha bon ??) je tiens à remercier ici officiellement ceux et celles sans qui ma nouvelle vie belge n’aurait pas été si gaie ;-) Ma deuxième maison, mon petit coin de paradis… là où, quoi qu’il se passe en dehors, les petits tracas quotidiens ou les plus gros chagrins d’une vie s’effacent comme par magie. Parce que cet endroit est essentiel à mon équilibre, et même si ses occupants ne liront probablement jamais ces lignes, je tiens à remercier toute la Ferme Rosier. Catherine bien sûr, pour nos longues discussions, tes conseils, et parce que je ne vois jamais le temps passer avec toi. Muriel et Charlotte pour votre confiance, Christel et son Brad, Caro la masseuse future ostéo et tout son clan, Fanfan, Slavie et ses chocolats, Cathy et sa belle espagnole, Claire et ses cours bien fatiguants mais tellement enrichissants du mardi soir, et bien d’autres… Tout le groupe des mi-vieilles pour votre amitié et le groupe des ados parce que vous me faites bien rire. Et bien sûr, tous les habitants à 4 pattes de la Ferme Rosier avec une pensée toute spéciale pour Channel et Génial. Channel, parce que tu as un sale caractère de jument mais que c’est justement ça que j’aime chez toi et parce que j’ai tant appris avec toi. Génial, parce que il y a des choses qui ne s’expliquent pas, parce il a fallu attendre 13 années pour te 4 ramener près de moi, parce que je compte bien profiter de chaque moment de tes « vieux » jours, parce que tu es mon p’tit gris. Avec toi j’oublie tout, et je suis juste là, posée entre ciel et terre, à une hauteur qui n’existe pas… Merci à mes amis français d’avoir toujours été là. Morgane, parce que 29 années d’amitié ne s’effacent pas avec la distance. Roz et ta grande famille, parce que même si on ne refait pas le monde des heures au téléphone, je sais que tu es toujours là quand il faut. Camille pour nos discussions très scientifiques (merci MSN hein) et parce que tu arrives toujours à me faire marrer devant mon écran d’ordinateur (et que je pense à ce moment que j’ai bien l’air idiote et que j’espère que personne ne passe dans le couloir). Je n’oublie pas tous les autres qui savent faire mentir l’adage « loin des yeux, loin du cœur »… Une petite pensée à Françoise pour avoir toujours su me remettre les genoux en place (et le reste…) et m’avoir appris à les ménager lors des séances de TP, sur les rochers de Wimereux et sur le dos de mon p’tit poney. Et son mari Daniel, pour nos discussions éthologiquement équines. Merci à toi mon naturaliste fou. Parce que je suis bien contente d’avoir levé les yeux du sol où je cherchais des insectes au moment où tu baissais les yeux du ciel où tu cherchais tes oiseaux… Le reste reste entre nous, tu le sais déjà, je n’ai pas besoin de l’écrire ici. Merci à mes parents pour m’avoir toujours soutenue dans mes choix et m’avoir appris à saisir la chance au vol et à croire en mes rêves. Le reste reste entre nous, bla bla bla ;-) Enfin, merci à ceux qui ont donné de leur temps pour la finalisation de cette thèse : vous les membres de mon jury. Joan, pour m’avoir fait confiance en 2004, pour m’avoir toujours suivie et encouragée, et pour avoir accepté d’être encore et toujours là lors de la finalisation de cette thèse. Comme on dit ici : un grand merci ! Jacques Brodeur et Emmanel Deshouant, merci à vous pour tous vos commentaires et vos remarques lors de la défense privée. Caroline, pour tes conseils, tes remarques, ton dynamisme, ça y est je suis prête pour finir les dessins du cours invertébrés (qu’on ne peut plus appeler invertébrés d’ailleurs!). Hans notre grand schtroumpf, aujourd’hui président du jury, merci pour les petits mots toujours sympas quand on se croisait dans les couloirs ;-) Une page se tourne, mais je n’en doute pas, de nouvelles opportunités arrivent et n’attendent qu’une chose : que je les saisissent au vol ! 5 6 Abstract The theory of sexual selection was formulated by Darwin (1871) to explain the origin of sexually dimorphic traits that are detrimental to survival.
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