scholarly journals THE GENETIC STRUCTURE OF NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER. XVII. A POPULATION CARRYING GENETIC VARIABILITY EXPLICABLE BY THE CLASSICAL HYPOTHESIS

Genetics ◽  
1984 ◽  
Vol 108 (2) ◽  
pp. 393-408
Author(s):  
Shinichi Kusakabe ◽  
Terumi Mukai
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Structure ◽  
Genetic Variability ◽  
Natural Populations ◽  
Experimental Results ◽  
Effective Size ◽  
Degree Of Dominance ◽  
Significant Difference ◽  
Deleterious Genes ◽  
Classical Hypothesis

ABSTRACT About 400 second chromosomes were extracted from the Aomori population, a northernmost population of D. melanogaster on Honshu in Japan, and the following experimental results were obtained. (1) The frequency of lethal chromosomes was 0.23. (2) The effective size of the population was estimated to be about 3000, from the allelism rate of lethal chromosomes and their frequency. (3) The detrimental and lethal loads for viability were 0.243 and 0.242, respectively, and the D/L ratio became 1.00. (4) The average degree of dominance for mildly deleterious genes was estimated to be 0.178 ± 0.056. (5) Additive (α2  A) and dominance (α2  D) variances of viability were estimated to be 0.00276 ± 0.00090 and 0.00011 ± 0.00014, respectively. (6) There was no significant difference in environmental variances between homozygotes and heterozygotes. Using these estimates, we discuss the maintenance mechanisms of genetic variability of viability in the population. The mutation-selection balance explained these experimental results.

THE GENETIC STRUCTURE OF NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER. XIV. EFFECTS OF THE INCOMPLETE DOMINANCE OF THE IN(2LR)SM1 (Cy) CHROMOSOME ON THE ESTIMATES OF VARIOUS GENETIC PARAMETERS

Genetics ◽  
1980 ◽  
Vol 94 (1) ◽  
pp. 169-184
Author(s):  
Terumi Mukai
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Structure ◽  
Mutation Rate ◽  
Homologous Chromosome ◽  
Genetic Parameters ◽  
Natural Populations ◽  
Incomplete Dominance ◽  
Degree Of Dominance

ABSTRACT Recent reports (MUKAI et al. 1974; KATZand CARDELLINO1978; COCKER-HAM and MUEAI 1978) have indicated that the Cy chromosome is not always dominant over its homologous chromosome with respect to viability. Thus,the genetic parameters previously estimated using viabilities determined by the Cy method are biased. In the present paper, the biases of the estimates for the polygenic mutation rate, the degree of dominance and the homozygous load are examined. The results indicate that the biases for the mutation rate and the degree ofdominance are small and that the estimate of the homozygous load relative to the average viability of the population is not biased.

scholarly journals ACCUMULATION OF DELETERIOUS GENES IN A CAGE POPULATION OF DROSOPHILA MELANOGASTER

Genetics ◽  
1977 ◽  
Vol 86 (3) ◽  
pp. 657-664
Author(s):  
Won Ho Lee ◽  
Takao K Watanabe
Keyword(s):  
Drosophila Melanogaster ◽  
Deleterious Effect ◽  
Natural Populations ◽  
Lethal Gene ◽  
Male Sterile ◽  
Effective Population ◽  
Population Number ◽  
Heterozygous Condition ◽  
Cage Population ◽  
Deleterious Genes

ABSTRACT 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.

scholarly journals A SEASONAL SURVEY OF THE GENETIC STRUCTURE IN NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER

1969 ◽  
Vol 44 (4) ◽  
pp. 247-258 ◽  
Author(s):  
KAZUHIKO KOSUDA ◽  
OSAMU KITAGAWA ◽  
DAIGORO MORIWAKI
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Structure ◽  
Natural Populations
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