"Adaptation capabilities of an invasive species, the Japanese oyster Crassostrea gigas in Brittany (France)" . "L\u2019hu\u00EEtre creuse du Pacifique Crassostrea gigas est une esp\u00E8ce d\u2019int\u00E9r\u00EAt \u00E9conomique en France. L\u2019extension de cette esp\u00E8ce pendant le dernier si\u00E8cle a rapidement conduit au d\u00E9veloppement de populations sauvages. C. gigas est, \u00E0 pr\u00E9sent, consid\u00E9r\u00E9e comme une esp\u00E8ce invasive dans de nombreuses r\u00E9gions du globe. L\u2019objectif principal de ce travail est de comprendre les capacit\u00E9s adaptatives de cette esp\u00E8ce, \u00E0 l\u2019aide d\u2019une approche g\u00E9n\u00E9tique et physiologique \u00E0 diff\u00E9rentes \u00E9chelles spatiales et temporelles. A macro-\u00E9chelle (le long des c\u00F4tes fran\u00E7aises) et \u00E0 micro-\u00E9chelle (bas et haut d\u2019estran), une diff\u00E9renciation g\u00E9n\u00E9tique significative a \u00E9t\u00E9 observ\u00E9e entre les population adultes \u00E0 l\u2019aide de marqueurs exoniques et allozymiques. A contrario, cette diff\u00E9rence n\u2019a pas d\u00E9cel\u00E9e par les microsatellites. Dans trois sites bretons, une structuration g\u00E9n\u00E9tique significative a \u00E9t\u00E9 observ\u00E9e entre les adultes et les jeunes recrues des ann\u00E9es 2005 et 2006, e \u00E9galement entre ces recrues et des naissains cultiv\u00E9s. Dans la seconde partie de cette \u00E9tude, plusieurs indicateurs physiologiques de sant\u00E9 et de la \u00AB fitness \u00BB ont \u00E9t\u00E9 estim\u00E9s sur des adultes des trois sites cit\u00E9s pr\u00E9c\u00E9demment. De fortes diff\u00E9rences significatives ont \u00E9t\u00E9 observ\u00E9es entre des individus de sexe et de stade de gam\u00E9togen\u00E8se diff\u00E9rent, au cours de l\u2019ann\u00E9e 2005. Cependant, aucune diff\u00E9rence majeure des performances physiologiques n\u2019a \u00E9t\u00E9 r\u00E9v\u00E9l\u00E9e entre les adultes \u00E0 micro- et macro-\u00E9chelles spatiales. En conclusion, l\u2019ensemble de ces r\u00E9sultats sugg\u00E8re un fort potentiel invasif de C. gigas, r\u00E9sultant d\u2019une plasticit\u00E9 ph\u00E9notypique et surtout d\u2019une s\u00E9lection locale appliqu\u00E9e sur sa forte diversit\u00E9 g\u00E9n\u00E9tique." . "Genotype" . "Cyster" . . . . "2008" . . "Physiology" . . . "Invasive" . . "Text" . "Crassostrea gigas -- Adaptation -- France -- Bretagne (France)" . "Adaptation" . . "Genetic" . . "Th\u00E8ses et \u00E9crits acad\u00E9miques" . . "The Pacific oyster Crassostrea gigas is an important commercial species in France. The wide distribution of this species during the last decade quickly led to the developmeht of \u201Cwild\u201D populations mainly in rocky intertidal areas. C. gigas is now considered an invasive species in various parts of the world. The main objective of this work was to characterize the adaptative capabilities of C. giqas in Brittany using genetic and physiological approaches at different spatial and temporal scales. Using exonic markers, significant genetic structures were observed between populations of adult oysters along the French coasts. In contrast, this difference was not observed using microsatellites. The study at the micro-scale, demonstrated no significant difference in allelic frequencies between oysters at high and low tidal heights, except at the MPI locus via allozymes analysis. At three sites f rom Brittany, significant genetic structure was observed between adult and juvenile oysters recruited in 2005 and 2006 and also between these same juveniles and cultivated spat. In the second part of this study, several physiological indicators of health and fitness-related traits were assessed on adults from the three sites described above. Strong significant differences were found between sex and gametogenesis stages throughout the year 2005. In contras no differential physiological performance was illustrated between adults at macro and micro-spatial scales. In conclusion, aIl of these results suggest a high potential of invasion for as that correspond to the compound of phenotypic plasticity and all above local selection applied to its high genetic diversity." . "Capacit\u00E9 d'adaptation d'une esp\u00E8ce invasive, l'hu\u00EEtre creuse du Pacifique Crassostrea gigas, en r\u00E9gion Bretagne" . . . "Capacit\u00E9 d'adaptation d'une esp\u00E8ce invasive, l'hu\u00EEtre creuse du Pacifique Crassostrea gigas, en r\u00E9gion Bretagne" . "Polymorphism" . "Phenotype" . .