tailieunhanh - báo cáo khoa học: "Changes in the distribution of the genetic variance of a quantitative trait in small populations of Drosophila melanogaster"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Changes in the distribution of the genetic variance of a quantitative trait in small populations of Drosophila melanogaster | 159 Genet. Sei. Evol. 1989 21 159-168 Elsevier INRA Original article Changes in the distribution of the genetic variance of a quantitative trait in small populations of Drosophila melanogaster J. Guerra and A. García Universidad Complutense Facultad de Ciencias Bioldgicas Departamento de Genética 28040 Madrid Spain received 28 March 1988 accepted 16 August 1988 Summary The coefficient of variation of the genetic variance at generation f CV VaỊị of an additive trait among replicated unselected small populations has been theoretically shown to be largely due to linkage disequilibrium from sampling Starting from a population in linkage equilibrium CV VAt should initially increase rapidly approaching an ăsymptotiệ value. However when effective population size expands CV Vạỉ is expected to decrease. Experiments with Drosophila melano-gaster were carried out to check these predictions. Inbred lines were established by brother-sister single pair matings and continued for 3 generations. Each line was then maintained with as many parents as possible up to generation 10. The trait considered was the total number of abdominal bristles on the 5th and the 6th stemites in generations 0 4 and 10 A single generation of divergent selection was carried out in each of 75 lines in the same generations. Assuming no differences in environmental variance between lines CV VAI can then be estimated from the within-line phenotypic variances or from the responses to selection. As predicted by theory the value of CV VAI substantially increased from generation 0 to 4. No reduction was detected afterwards possibly because the trait was affected by blocks of genes. Other predictions made concerning the redistribution of the genetic variance have been substantiated. Inbreeding - genetic variance - Drosophila melanogaster Résumé Changements de la distribution de la variance génétlque d un caractère quantlta-tif dans des populations d effectif limité de Drosophila melanogaster. On a