ACCUMULATION OF DELETERIOUS GENES IN A CAGE POPULATION OF DROSOPHILA MELANOGASTER

[摘要] Lethal and sterility mutations were accumulated in a cage population which was initiated with lethal- and sterility-free second chromosomes of D. melanogaster . It took about 2,000 days for the frequencies of these genes to reach equilibrium levels, i.e. , 18% lethal and 9% male-sterile chromosomes. Two other cage populations which were initiated with random chromosomes sampled from natural populations and kept for more than eleven years in the laboratory showed 19-20% lethal content. The elimination rates of lethals by homozygosis in these populations were smaller than the mutation rate. By using Nei's formulae, the deleterious effect of a lethal gene in heterozygous condition ( h ) was estimated to be 0.035. The effective population number in the cage populations was estimated to be 1,000-2,900, while the actual population number was 3,500-7,800.

[学科分类] 医学（综合）