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Genre/Form: | Thèses et écrits académiques |
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Material Type: | Thesis/dissertation |
Document Type: | Book |
All Authors / Contributors: |
Jessica Côte; Jean-Marc Roussel; Agrocampus Ouest |
OCLC Number: | 868069987 |
Notes: | Thèse soutenue à AGROCAMPUS-OUEST sous le sceau de l'Université Européenne de Bretagne. |
Description: | 1 vol. (185 p.) : ill. ; 25 cm. |
Responsibility: | Jessica Côte ; sous la dir. de Jean-Marc Roussel. |
Abstract:
This thesis investigates the potential of adaptive responses of four Atlantic salmon (Salmo salar) populations in France. For each population, the effects of dissolved oxygen level and water temperature on early life history traits were measured during the embryonic development. The study populations are genetically differentiated and dwell in contrasted hydrological, geo-morphological and thermal environments. Within and between populations crosses were performed to compare responses of F1 offspring reared under controlled conditions. Within-population crosses revealed a high plasticity and tolerance to hypoxia and water temperature of study populatins. Observed population x environment and genotype x environment interactions showed that populations differ in their ability to respond to environmental stress, and suggested a genetic basis for phenotypic plasticity. A comparative Qst-Fst approach revealed that divergent selection was probably involved in the phenotypic differentiation of populations studied. We detected effects of both heterosis and outbreeding depression depending on traits when inter-population hybrid embryos were incubated under stressful conditions. The effects of outbreeding depression were predominant over embryonic development, suggesting local adaptation of populations studied. We also investigated the consequences of interspecific hybridization by cross-fertilizing salmon and brown trout Salmo trutta. Higher performances of hybrids were recorded under stressful oxygen conditions, suggesting that salmon genetic introgression by trout could be enhanced by on-going changes in riverine habitats at a global scale.
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