tailieunhanh - báo cáo khoa học: "Population genetics of French brown trout (Salmo trutta L): large geographical differentiation of wild populations and high similarity of domesticated stocks"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Population genetics of French brown trout (Salmo trutta L): large geographical differentiation of wild populations and high similarity of domesticated stocks | Génét. Sél. Evol. 1985 17 2 225-242 Population genetics of French brown trout Salmo trutta L large geographical differentiation of wild populations and high similarity of domesticated stocks Francine KRIEG and R. GUYOMARD . Laboratoire de Physiologic des Poissons Centre de Recherches zootechniques F 78350 Jouy-en-Josas Summary The genetic variability of 7 fish-farm strains and 14 wild populations of brown trout was studied by electrophoretic analysis of 23 enzyme systems coded for by 52 loci. The total gene diversity was high as compared to other salmonid species but only 45 p. 100 was found within the populations indicating an extreme genetic differentiation in brown trout. Upgma clustering analysis subdivided the populations into 4 major groups . 2 in Corsica 1 in Brittany and a 4 th one closely clustering the Norman wild anadromous populations with the hatchery strains. These results suggest that Breton and Corsican samples represent native stocks but that some hatchery introgression or contamination is possible in Norman rivers. This last assumption could explain the coexistence of 2 electro-phoretically differentiated ecotypes in one Norman drainage. The genetic distances between Corsican and continental samples are consistent with previous meristic studies reporting the occurrence of a differentiated form in Corsica. According to the heterozygosity level and genetic distance values a severe bottleneck effect is unlikely to have occurred except in one of the wild populations. The hatchery strains showed a high genetic similarity which could be interpreted as a founder effect by an initial sampling in a restricted area of the species range. Key words Electrophoretic variation population genetics Salmo trutta L. Resume Génétique des populations franpaises de truite fario Salmo trutta L. forte differentiation géographique des populations naturelles et similitude génétique des souches d elevage La variatibilité électrophorétique de 23 systèmes .