scholarly journals THE GENETIC VARIABILITY OF THIRD CHROMOSOMES IN A LOCAL POPULATION OF DROSOPHILA MELANOGASTER

Genetics ◽  
1976 ◽  
Vol 82 (1) ◽  
pp. 63-82
Author(s):  
Takao K Watanabe ◽  
Osamu Yamaguchi ◽  
Terumi Mukai
Keyword(s):  
Drosophila Melanogaster ◽  
Balancing Selection ◽  
Local Population ◽  
Load Ratio ◽  
Average Degree ◽  
Large Cage ◽  
Degree Of Dominance ◽  
Cage Population ◽  
The Difference ◽  
Lethal Genes

ABSTRACT Five hundred and two third chromosomes were extracted from a large cage population of Drosophila melanogaster initiated two months after collection of the progenitors near Raleigh, North Carolina in 1970.—Salivary gland chromosomes of 489 chromosome lines were examined and 54 chromosomes were found to carry inversions. The inversions were classified into three polymorphic types [In(3L)P, In(3R)P, and In(3R)C] and two unique types. The polymorphic inversions were found in frequencies of 0.012, 0.088, and 0.010, respectively.—Viabilities of homozygotes and heterozygotes were examined. Chromosomes with lethals occurred with a frequency of 0.495: 0.537 in the group of inversion-carrying chromosomes and 0.490 in the group of inversion-free chromosomes. The average homozygote viability computed on the basis of an average heterozygote viability of 1.0000 was 0.3235 if lethal lines were included and 0.6290 if they were excluded. The detrimental load to lethal load ratio (D:L ratio) was 0.70 (=0.4636-0.6650). The average viability of lethal heterozygotes was significantly larger than that of lethal-free heterozygotes. It appears, however, that lethal genes in heterozygotes have deleterious effects on fitness as a whole.—The average degree of dominance for viability polygenes was estimated to be about 0.3-0.4 in lethal-free individuals and nearly zero in lethal heterozygotes. Overdominance or some form of balancing selection was suggested at some loci. The difference between the values obtained for average degree of dominance due to genetic backgrounds and superior vibaility of lethal heterozygotes (but not fitness as a whole) suggests that some epistasis or coadaptation occurs.—The results described above are similar to those obtained for the second chromosomes (Mukai and Yamaguchi 1974).

scholarly journals THE GENETIC STRUCTURE OF NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER. XI. GENETIC VARIABILITY IN A LOCAL POPULATION

Genetics ◽  
1974 ◽  
Vol 76 (2) ◽  
pp. 339-366
Author(s):  
Terumi Mukai ◽  
Osamu Yamaguchi
Keyword(s):  
North Carolina ◽  
Salivary Gland ◽  
Genetic Variability ◽  
Local Population ◽  
Natural Populations ◽  
Load Ratio ◽  
Mutation Rates ◽  
Degree Of Dominance ◽  
Carolina Population ◽  
Lethal Genes

ABSTRACT Six hundred and ninety-one second chromosomes were extracted from a Raleigh, North Carolina population, and the following experimental results were obtained: (1) Salivary gland chromosomes of all lines were observed and the number of inversion-carrying chromosomes was 130, among which 76 carried In(2R)NS, 36 carried In(2L)t, 4 carried In(2L)t and In(2R)NS, and 14 carried different kinds of rare inversions. (2) Viabilities of homozygotes and heterozygotes were examined. The frequency of lethal-carrying chromosomes was 275/691 (or 0.398):70/130 (or 0.538) in inversion-carrying chromosomes and 205/561 (or 0.365) in inversion-free chromosomes. The former is significantly higher than the latter. The average homozygote viability was 0.4342 including lethal lines and 0.7163 excluding those, the average heterozygote viability being 1.0000. The detrimental load to lethal load ratio (D:L ratio) was 0.334/0.501 = 0.67. The average viability of lethal heterozygotes was less than that of lethal-free heterozygotes, significantly in inversion-free individuals but not significantly so in inversion-carrying individuals. Inversion heterozygotes seem to have slightly better viability than the inversion-free heterozygotes on the average, but not significantly so. (3) The average degree of dominance of viability polygenes was estimated to be 0.293 ± 0.071 for all heterozygotes whose component chromosomes had better viabilities than 0.6 of the average heterozygote viability, 0.177 ± 0.077 for inversion-free heterozygotes and 0.489 ± 0.082 for inversion heterozygotes. (4) Mutation rates of viability polygenes and lethal genes were estimated on the basis of genetic loads and average degrees of dominance of lethal genes and viability polygenes. Estimates were very close to those obtained by direct estimation. (5) Possible overdominance and epistasis were detected, but the magnitude must be very small. (6) The effective size of the population was estimated to be much greater than 10,000 by using the allelism rate of lethal-carrying chromosomes (0.0040) and their frequency.—On the basis of these findings and the comparison with the predicted result (Mukai and Maruyama 1971), the mechanisms of the maintenance of genetic variability in the population are discussed.

scholarly journals THE ALCOHOL DEHYDROGENASE POLYMORPHISM IN POPULATIONS OF DROSOPHILA MELANOGASTER. I. SELECTION IN DIFFERENT ENVIRONMENTS

Genetics ◽  
1978 ◽  
Vol 90 (1) ◽  
pp. 161-191
Author(s):  
W van Delden ◽  
A C Boerema ◽  
A Kamping
Keyword(s):  
Drosophila Melanogaster ◽  
Alcohol Dehydrogenase ◽  
Experimental Evidence ◽  
Balancing Selection ◽  
Adult Survival ◽  
High Survival ◽  
High Humidity ◽  
Allozyme Polymorphism ◽  
Degree Of Dominance ◽  
Frequency Changes

ABSTRACT The allozyme polymorphism at the alcohol dehydrogenase locus in Drosophila melanogaster was studied in order to obtain experimental evidence about the maintenance of this polymorphism. Populations started with different initial allele frequencies from homozygous F and S lines showed a convergence of frequencies on regular food at 25°, leading to values equal to those in the base populations. These results were interpreted as due to some kind of balancing selection. In populations kept at 29.8°, a lower equilibrium F frequency was attained. Addition of ethanol and some other alcohols to the food gave a rapid increase in F frequency, and high humidity decreased the F frequency slightly. Combination or alternation of ethanol and high humidity had variable effects in the populations tested. For a further analysis of the allele-frequency changes, estimates were obtained for egg-to-adult survival under different conditions and for adult survival on ethanol-supplemented food. On ethanol food (both at regular and high humidity), egg-to-adult survival of SS homozygotes was considerably lower than that of the FF and FS genotypes. Under regular conditions of food, temperature and humidity, a tendency to heterozygote superiority was observed, while at high humidity a relative high survival of SS was noticed in some tests. Adult survival of SS was lower than that of FF, but FS was generally intermediate, though the degree of dominance differed between populations. The results are consistent with the hypothesis of the occurrence of selection at the Adh locus.

scholarly journals THE GENETIC STRUCTURE OF NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER. XII. LINKAGE DISEQUILIBRIUM IN A LARGE LOCAL POPULATION

Genetics ◽  
1974 ◽  
Vol 77 (4) ◽  
pp. 771-793
Author(s):  
Terumi Muki ◽  
Takao K Watanabe ◽  
Osamu Yamaguchi
Keyword(s):  
Drosophila Melanogaster ◽  
Local Population ◽  
Natural Populations ◽  
Large Cage ◽  
Linkage Disequilibria ◽  
Esterase 6 ◽  
Relative Viability ◽  
Carolina Population ◽  
Isozyme Loci ◽  
Glycerol 3 Phosphate Dehydrogenase

ABSTRACT Seven hundred and three second chromosomes were extracted from a Raleigh, North Carolina population of Drosophila melanogaster in 1970. Additionally, four hundred and eighty-nine third chromosomes were extracted from a large cage population founded from the flies in the 1970 Raleigh collection. The α glycerol-3-phosphate dehydrogenase-1, malate dehydrogenase-1, alcohol dehydrogenase, and α amylase loci were studied from the second chromosomes, and the esterase-6, esterase-C, and octanol dehydrogenase loci were analyzed from the third chromosomes. Inversions, relative viability and fecundity were studied for both classes of chromosomes. The following significant findings were obtained: (1) All loci examined were polymorphic or had at least two alleles at appreciable frequencies. Analysis of the combined data from this experiment with that of Mukai, Mettler and Chigusa (1971) revealed that the frequencies of the genes in the second chromosomes collected in early August were approximately the same over three years. (2) Linkage disequilibria between and among isozyme genes inter se were not detected except in a few cases which can be considered due to non-random sampling. (3) Linkage disequilibria between isozyme genes and polymorphic inversions were detected when the recombination values between the breakage points of the inversions and the genes in question were small. In only a few cases, were second and third order linkage disequilibria including polymorphic inversions detected. (4) Evidence for either variation among genotypes within loci or cumulative effects of heterozygosity was found for viability and fecundity. As a result of these findings, it was tentatively concluded that although selection might be perceptibly operating on some polymorphic isozyme loci, most of the polymorphic isozyme genes are selectively neutral or near-neutral in the populations studied.

Inheritance of Some Morphological Characteristics of Parental Lines in Mustard-Rape Hybrid

2020 ◽  
pp. 23-30
Keyword(s):  
First Generation ◽  
Agronomic Traits ◽  
Morphological Characteristics ◽  
Morphological Characters ◽  
Hybrid Plant ◽  
Distant Hybridization ◽  
Degree Of Dominance ◽  
Whole Plant ◽  
Row Width ◽  
The Difference

Distant hybridization is known to play an important role in expanding the gene pool of any crop. It is believed that the combination of different genomes in one nucleus, as a rule, is accompanied by the phenomenon of “genomic shock”, resulting in a variety of genetic and epigenetic changes. This provides a wealth of material for the selection of genotypes adapted to different environmental conditions. Interspecific hybrids in different combinations were obtained in the genus Brassica, however, until now, interest in distant hybridization in this genus has not died out, since such important crops as rapeseed and mustard demand an improvement of many important agronomic traits. The aim of this work was to study the degree of manifestation of morphological characters of a leaf, flower, and plant as a whole in the hybrid obtained by crossing of brown mustard of the variety Slavyanka and a collection specimen of spring rape. Seeds were sown in the spring of 2019 in a field with 30 cm row width. During the flowering period a number of morphological characters of a flower, leaf, and the whole plant were analyzed. Each parameter was evaluated with 10 plants. The degree of dominance in first-generation hybrid was calculated by the formula of Beil, Atkins (1965). The dominance coefficients were not determined in the case when the difference between the parental samples was insignificant. Differences between parental samples were determined by Student t-test. The level of heterosis was calculated according to the formula of Rasul et al (2002). In a mustard-rapeseed hybrid, the size of the leaves of the lower row was inherited by the type of rapeseed, which had larger leaves than mustard. The height of the hybrid plant was inherited by the type of mustard (hp = 1.32, Ht = 4.89%), and intermediate inheritance was observed for the length of the internodes (hp = -0.48). The size of the flower petals and sepals was inherited by the type of rapeseed, and significant heterosis was observed for the length of the pistil (Ht = 33.57%). The data obtained are of interest for understanding the interaction of genes of different genomes in the genus Brassica.

scholarly journals The Rate of Mutation and the Homozygous and Heterozygous Mutational Effects for Competitive Viability: A Long-Term Experiment With Drosophila melanogaster

Genetics ◽  
2001 ◽  
Vol 158 (2) ◽  
pp. 681-693 ◽  
Author(s):  
David Chavarrías ◽  
Carlos López-Fanjul ◽  
Aurora García-Dorado
Keyword(s):  
Drosophila Melanogaster ◽  
Minimum Distance ◽  
Deleterious Mutations ◽  
Regression Estimate ◽  
Term Experiment ◽  
Degree Of Dominance ◽  
Long Term Experiment ◽  
Rate Of Decline ◽  
Good Agreement

Abstract The effect of 250 generations of mutation accumulation (MA) on the second chromosome competitive viability of Drosophila melanogaster was analyzed both in homozygous and heterozygous conditions. We used full-sib MA lines, where selection hampers the accumulation of severely deleterious mutations but is ineffective against mildly deleterious ones. A large control population was simultaneously evaluated. Competitive viability scores, unaffected by the expression of mutations in heterozygosis, were obtained relative to a Cy/L2 genotype. The rate of decline in mean ΔM ≈ 0.1% was small. However, that of increase in variance ΔV ≈ 0.08 × 10-3 was similar to the values obtained in previous experiments when severely deleterious mutations were excluded. The corresponding estimates of the mutation rate λ ≥ 0.01 and the average effect of mutations E(s) ≤ 0.08 are in good agreement with Bateman-Mukai and minimum distance estimates for noncompetitive viability obtained from the same MA lines after 105 generations. Thus, competitive and noncompetitive viability show similar mutational properties. The regression estimate of the degree of dominance for mild-to-moderate deleterious mutations was ∼0.3, suggesting that the pertinent value for new unselected mutations should be somewhat smaller.

The Study of Differential Pricing Model in Market of Urban Taxi Industry Based on the Zoning Service

2014 ◽  
Vol 587-589 ◽  
pp. 1932-1939
Author(s):  
Qi Yuan Liu ◽  
Liang Jie Xu ◽  
Dan Ying
Keyword(s):  
Load Ratio ◽  
Return Rate ◽  
Pricing Model ◽  
Trip Distribution ◽  
Model Based ◽  
Taxi Service ◽  
Differential Pricing ◽  
The Difference ◽  
Taxi Industry ◽  
Negative Phenomena

In some cities, the zoning operation in taxi service leads to the difference in load ratio and empty return rate in their limited zones. Therefore, some negative phenomena appear such as the instability of drivers’ income and drivers negotiate the price without taximeter. In order to keep a balance between enhancing the drivers’ profit and protecting the passengers’ interests, establishing a differential pricing model based on the characteristics of taxi service in different zones. The operation areas, trip intensity and trip distribution have been taken into consideration about different taxi service zones in the model.

Testing for Asymmetrical Gene Flow in aDrosophila melanogasterBody-Size Cline

Genetics ◽  
2003 ◽  
Vol 165 (2) ◽  
pp. 667-673 ◽  
Author(s):  
W Jason Kennington ◽  
Julia Gockel ◽  
Linda Partridge
Keyword(s):  
Drosophila Melanogaster ◽  
Gene Flow ◽  
Body Size ◽  
Genetic Parameter ◽  
Good Evidence ◽  
Microsatellite Data ◽  
Eastern Australia ◽  
The Difference ◽  
Two Populations ◽  
Private Alleles

AbstractAsymmetrical gene flow is an important, but rarely examined genetic parameter. Here, we develop a new method for detecting departures from symmetrical migration between two populations using microsatellite data that are based on the difference in the proportion of private alleles. Application of this approach to data collected from wild-caught Drosophila melanogaster along a latitudinal body-size cline in eastern Australia revealed that asymmetrical gene flow could be detected, but was uncommon, nonlocalized, and occurred in both directions. We also show that, in contrast to the findings of a previous study, there is good evidence to suggest that the cline experiences significant levels of gene flow between populations.

scholarly journals THE EFFECTS OF HETEROZYGOSITY CHANGES ON VIABILITY IN DROSOPHILA MELANOGASTER

Genetics ◽  
1972 ◽  
Vol 70 (4) ◽  
pp. 595-610
Author(s):  
Ray Moree
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Background ◽  
Laboratory Strain ◽  
Theoretical Expectation ◽  
Wild Type ◽  
Small Deviations ◽  
The Third ◽  
The Difference

ABSTRACT The viability effects of chromosomes from an old and from a new laboratory strain of D. melanogaster were studied in eight factorial combinations and at two heterozygosity levels. The combinations were so constructed that heterozygosity level could be varied in the third chromosomes of the carriers of a homozygous lethal marker, in the third chromosomes of their wild-type segregants, and in the genetic backgrounds of both. Excluding the effect of the marker and the exceptional outcomes of two of the combinations, and taking into account both large and small deviations from theoretical expectation, the following summary is given as the simplest consistent explanation of the results: 1) If total heterozygosities of two segregant types tend toward equality their viabilities tend toward equality also, whether background heterozygosity is high or low; if background heterozygosities is higher the tendency toward equality is slightly greater. 2) If total heterozygosity of two segregant types are unequal the less heterozygous type has the lower viability; the difference is more pronounced when background heterozygosity is low, less when it is high. 3) Differences between segregant viabilities are correlated with differences between the total heterozygosities of the two segregants; genetic background is effective to the extent, and only to the extent, that it contributes to the magnitude of this difference. This in turn appears to underlie, at least partly, the expression of a pronounced interchromosomal epistasis. Thus in this study viability is seen to depend upon both the quantity and distribution of heterozygosity, not only among the chromosomes of an individual but among the individuals of a given combination as well.

scholarly journals Joint regulation of cell size and cell number in the wing blade of Drosophila melanogaster

1997 ◽  
Vol 69 (1) ◽  
pp. 61-68 ◽  
Author(s):  
JENNIE McCABE ◽  
VERNON FRENCH ◽  
LINDA PARTRIDGE
Keyword(s):  
Drosophila Melanogaster ◽  
Significant Negative Correlation ◽  
Cell Number ◽  
Negative Association ◽  
Cell Area ◽  
Wing Area ◽  
Compensatory Control ◽  
Significant Difference ◽  
The Difference ◽  
Compensatory Regulation

We used Drosophila melanogaster to test for compensatory control of cell area and cell number in the regulation of total wing area. In two random bred wild-type base stocks collected from different geographic locations we found a negative association between the area and the number of cells in the wing blade. Three replicate lines were selected for increased or decreased wing area, with cell area maintained at the same level as in the three controls. After eight generations of selection, despite a large and highly significant difference in wing area between the large, control and small selection lines, cell area did not differ significantly between them. Rather, the difference in wing area between selection regimes was attributable to differences in cell number. Over the course of selection, the initially significant negative correlation between cell area and cell number in the wing increased, providing evidence for compensatory regulation of cell area and cell number. As a result of the increasingly negative association between the two traits, the variance in wing area declined as selection proceeded. It will be important to discover the mechanisms underlying the compensatory regulation of cell area and cell number.

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