Structure génétique, réponses bioénergétiques et traits de vie, de populations de flets (Platichthys flesus) soumises au réchauffement climatique, sur un gradient latitudinal

Abstract : The European flounder (Platichthys flesus) is a catadromous fish species distributed along the North-East Atlantic coasts, from the Arctic polar circle to the Iberian Peninsula. For several decades, the southern limit of its distribution area is shifting towards the North of the Portuguese coast. A preliminary study on the flounder population biology has detected a specific energetic metabolism for a southern peripheral population in Portugal compared to Northern populations located in the Bay of Biscay and in the Channel. In the present study, we have combined population genetics with experimental challenges in the laboratory to improve our knowledge on the genetic structure of flounder populations over Europe, and on the potentially resulting phenotypic differences among populations, mainly considering bioenergetics and life-history traits. The polymorphism of microsatellite markers and of several candidate genes highlighted a significant genetic differentiation between Iberian Peninsula populations and Northen populations. A thermal and hypoxia challenge has been conducted on flounder juveniles, considering (1) enzymatic activities linked to energetic metabolism (aerobiosis and anaerobiosis) and anabolism, and (2) a proteomic approach; this common garden experiment suggested a higher capacity of central populations (from Canche and Vilaine, France) and of one peripheral Southern population (from Lima, Portugal) to cope with respectively cold condition, warm and hypoxia condition. Finally, the analysis of thermal reaction norms in fish early life history traits, considering embryo-larval stages submitted to a thermal gradient, underlined a possible local adaptation of the flounder populations to their thermal environments.
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Nicolas Pédron. Structure génétique, réponses bioénergétiques et traits de vie, de populations de flets (Platichthys flesus) soumises au réchauffement climatique, sur un gradient latitudinal. Sciences de la Terre. Université de Bretagne occidentale - Brest, 2016. Français. ⟨NNT : 2016BRES0058⟩. ⟨tel-01431379⟩

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