scholarly journals LINKAGE DISEQUILIBRIUM AND HETEROSIS IN EXPERIMENTAL POPULATIONS OF DROSOPHILA MELANOGASTER WITH PARTICULAR REFERENCE TO THE SEPIA GENE

1964 ◽  
Vol 39 (5) ◽  
pp. 289-305 ◽  
Author(s):  
SADAO CHIGUSA ◽  
TERUMI MUKAI
Keyword(s):  
Drosophila Melanogaster ◽  
Linkage Disequilibrium ◽  
Experimental Populations

scholarly journals Linkage disequilibrium in natural and experimental populations of Drosophila melanogaster.

Genetics ◽  
1988 ◽  
Vol 120 (4) ◽  
pp. 1043-1051
Author(s):  
Z Smit-McBride ◽  
A Moya ◽  
F J Ayala
Keyword(s):  
Drosophila Melanogaster ◽  
Linkage Disequilibrium ◽  
Assay Method ◽  
Effective Population ◽  
Population Mixing ◽  
Locus Pair ◽  
Two Samples ◽  
In The Wild ◽  
Population Sizes ◽  
Experimental Populations

Abstract We have studied linkage disequilibrium in Drosophila melanogaster in two samples from a wild population and in four large laboratory populations derived from the wild samples. We have assayed four polymorphic enzyme loci, fairly closely linked in the third chromosome: Sod Est-6, Pgm, and Odh. The assay method used allows us to identify the allele associations separately in each of the two homologous chromosomes from each male sampled. We have detected significant linkage disequilibrium between two loci in 16.7% of the cases in the wild samples and in 27.8% of the cases in the experimental populations, considerably more than would be expected by chance alone. We have also found three-locus disequilibria in more instances than would be expected by chance. Some disequilibria present in the wild samples disappear in the experimental populations derived from them, but new ones appear over the generations. The effective population sizes required to generate the observed disequilibria by randomness range from 40 to more than 60,000 individuals in the natural population, depending on which locus pair is considered, and from 100 to more than 60,000 in the experimental populations. These population sizes are unrealistic; the fact that different locus-pairs yield disparate estimates within the same population argues against the likelihood that the disequilibria may have arisen as a consequence of population bottlenecks. Migration, or population mixing, cannot be excluded as the process generating the disequilibria in the wild samples, but can in the experimental populations. We conclude that linkage disequilibrium in these populations is most likely due to natural selection acting on the allozymes, or on loci very tightly linked to them.

scholarly journals DYNAMICS OF CORRELATED GENETIC SYSTEMS. V. RATES OF DECAY OF LINKAGE DISEQUILIBRIA IN EXPERIMENTAL POPULATIONS OF DROSOPHILA MELANOGASTER

Genetics ◽  
1980 ◽  
Vol 94 (1) ◽  
pp. 217-234
Author(s):  
M T Clegg ◽  
J F Kidwell ◽  
C R Horch
Keyword(s):  
Drosophila Melanogaster ◽  
Linkage Disequilibrium ◽  
Isocitrate Dehydrogenase ◽  
Gene Frequency ◽  
Experimental Results ◽  
Frequency Distributions ◽  
Marker Loci ◽  
Experimental Populations ◽  
Selective Effects ◽  
F Statistics

ABSTRACT The dynamic behavior of four-locus gametic frequency distributions was studied in five replicate cage populations of Drosophila melanogaster for up to 50 generations. The joint frequency distributions were resolved into gene freqcencies and various disequilibrium measures. In addition, F statistics for marginal single-locus genotypic frequency distributions were followed through time. The gene frequency, disequilibrium and F statistics were obtained for four chromosome 3 enzyme marker loci [isocitrate dehydrogenase (3-27.1), esterase4 (3-36.8). phosphoglucomutase (343.4) and esterase-c (3-49.0)]. The initial structure of the experimental populations featured random mating proportions, and two complementary gametic types with respect to the marker loci, thus assuring complete pairwise linkage disequilibrium among the markers.—The experimental results indicate: (1) the between-replicate variance in gene frequency varied substantially among loci, with isocitrate dehydrogenase showing the greatest between-replicate variance, and esterase-C the least. (2) The F statistics initially were strongly negative but decayed to the neighborhood ofzero for all marker lociexcept esterase-C. The rate at which the F statistics approached zero varied among the marker loci, indicating substantial differences in the distribution of selective effects along the chromosome. The centromeric region, marked by esterase-C, shows the strongest selective effects. (3)The rate of decay 3flinkage disequilibrium was much faster than expected for pairs of neutral loci, averaging 1.82times the neutral rate over all replicates and pairs of loci. This acceleration, which was observed for all six pairwise combinations of loci, was interpreted asresulting from the interaction bctween selection and recombination. Our experimental results are consistent with many investigations of linkage disequilibrium in natural populations of Drosophila melanogasler that show little or no disequilibrium among enzyme loci. (4) Afortuitous contamination of two cages revealed an apparent regulatory interaction between the migrant and nonmigrant chromosomes at the esterase-C locus. The migrant chromosomes were very rapidly absorbed into the recipient populations, despite this interaction. This result suggests that the dynamics of migration in populations may be phenomenologically richer than anticipated by simple theory.

Phosphoglucomutase (PGM) and Esterase-6 (EST-6) alleles in Drosophila melanogaster: An attempt to detect linkage disequilibrium

Genetica ◽  
1978 ◽  
Vol 49 (2-3) ◽  
pp. 225-227 ◽  
Author(s):  
G. Trippa ◽  
G. A. Danieli ◽  
R. Costa ◽  
R. Scozzari
Keyword(s):  
Drosophila Melanogaster ◽  
Linkage Disequilibrium ◽  
Esterase 6

scholarly journals PROPERTIES AND EVOLUTIONARY POTENTIAL OF NEWLY INDUCED TANDEM DUPLICATIONS IN DROSOPHILA MELANOGASTER

Genetics ◽  
1982 ◽  
Vol 102 (1) ◽  
pp. 75-89
Author(s):  
Paul A Roberts ◽  
David J Broderick
Keyword(s):  
Drosophila Melanogaster ◽  
Linkage Disequilibrium ◽  
Tandem Duplication ◽  
Polytene Chromosomes ◽  
Primary Source ◽  
Evolutionary Potential ◽  
X Ray ◽  
Fitness Effects ◽  
New Genes ◽  
Tandem Duplications

ABSTRACT Most of some 33 X-ray-induced duplications recovered as Suppressors of Minute loci proved to be direct tandem duplications. When heterozygous, most duplications were crossover suppressors, and duplications of short to moderate size did not reduce the fitness of their bearers. Crossover suppression by tandem duplication may be attributed to intrastrand foldbacks of the type regularly seen in somatic polytene chromosomes. As a consequence, linkage disequilibrium between duplicated elements and normal chromosomes should be more profound than has been supposed. Tandem duplications appear to be predisposed by reason of frequency of generation, crossover suppression and fitness effects to serve as the primary source of new genes.

scholarly journals Linkage disequilibrium in experimental populations of Drosophila simulans: a test of the random drift hypothesis

1987 ◽  
Vol 50 (3) ◽  
pp. 187-193
Author(s):  
Catherine Montchamp-Moreau ◽  
Mariano Katz
Keyword(s):  
Linkage Disequilibrium ◽  
Genetic Drift ◽  
Natural Populations ◽  
Aldehyde Oxidase ◽  
Drosophila Simulans ◽  
Random Drift ◽  
Esterase 6 ◽  
Experimental Populations ◽  
Experimental Values ◽  
Neutralist Hypothesis

SummaryLinkage disequilibrium between five polymorphic enzymic loci of the third chromosome (Esterase-6, Phosphoglucomutase, Esterase-C, Aldehyde Oxidase and Acid Phosphatase) was studied in experimental populations of Drosophila simulans. Gametic data were obtained by mating sampled males with homozygous females at the five loci. Four cage populations were initiated with flies caught from natural populations. Extensive linkage disequilibrium was detected after 25 or 34 generations. The effective size of these populations was estimated about 400. Monte-Carlo simulations were performed in order to determine whether the observed disequilibria could be due to genetic drift. The observed probability distribution of the experimental values of r (the gametic correlation coefficient) was consistent with the distribution expected under random genetic drift. Our results are thus in accordance with the neutralist hypothesis.

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