scholarly journals SELECTION FOR REDUCED CROSSING OVER IN DROSOPHILA MELANOGASTER

Genetics ◽  
1974 ◽  
Vol 76 (3) ◽  
pp. 447-451
Author(s):  
Nasr F Abdullah ◽  
Brian Charlesworth
Keyword(s):  
Drosophila Melanogaster ◽  
Regression Coefficient ◽  
Selection Line ◽  
Crossing Over ◽  
Base Population ◽  
The Third ◽  
Significant Difference ◽  
Selection For ◽  
Significant Regression ◽  
Recombination Value

ABSTRACT Selection was practiced for reducing crossing over between the third chromosome genes Sb and H2 of Drosophila melanogaster, the method employed was to select the repulsion double heterozygotes Sb+/+H2 every generation. Two replicate selection lines were maintained. After 24 generations of selection, Line 1 showed no significant difference from the control, although the regression of recombination value on generation was significant. In generation 20, Line 2 had a significantly lower recombination value than the control, as well as having a highly significant regression coefficient. No chromosome rearrangements were involved in the response. It was concluded that there was substantial genic variability in the frequency of crossing over between Sb and H2 in the base population.

scholarly journals Polygenic and single gene responses to selection for resistance to diazinon in Lucilia cuprina.

Genetics ◽  
1992 ◽  
Vol 130 (3) ◽  
pp. 613-620 ◽  
Author(s):  
J A McKenzie ◽  
A G Parker ◽  
J L Yen
Keyword(s):  
Resistant Strain ◽  
Single Gene ◽  
Natural Populations ◽  
Susceptible Strain ◽  
Selection Line ◽  
Base Population ◽  
Gene Response ◽  
Biochemical Profiles ◽  
Resistant Strains ◽  
Selection For

Abstract Following mutagenesis with ethyl methanesulfonate, selection in a susceptible strain with a concentration of the insecticide diazinon (0.0004%, w/v) above that required to kill 100% of the susceptible strain, the LC100 of that strain, resulted in a single gene response. The resultant four mutant resistant strains have equivalent physiological, genetical and biochemical profiles to a diazinon-resistant strain derived from a natural population and homozygous for the Rop-1 allele. Modification of the microsomal esterase E3 is responsible for resistance in each case. The Rop-1 locus maps approximately 4.4 map units proximal to bu on chromosome IV. Selection within the susceptible distribution, at a concentration of diazinon [0.0001% (w/v)] less than the LC100, resulted in a similar phenotypic response irrespective of whether the base population had been mutagenized. The responses were polygenically based, unique to each selection line and independent of Rop-1. The relevance of the results to selection for insecticide resistance in laboratory and natural populations is discussed.

scholarly journals SELECTION FOR MALE RECOMBINATION IN DROSOPHILA MELANOGASTER

Genetics ◽  
1976 ◽  
Vol 84 (2) ◽  
pp. 333-351
Author(s):  
Margaret G Kidwell ◽  
J F Kidwell
Keyword(s):  
Drosophila Melanogaster ◽  
Centromeric Region ◽  
Major Effect ◽  
Specific Region ◽  
Correlated Responses ◽  
Male Recombination ◽  
The Third ◽  
High Line ◽  
Two Component ◽  
Selection For

ABSTRACT Two-way selection for male recombination over seven intervals of the third chromosome in Drosophila melanogaster was practiced for nine generations followed by relaxed selection for five generations. Significant responses in both directions were observed but these mainly occurred in early generations in the low line and in later generations in the high line. Divergence of male recombination frequencies between the two selection lines was not restricted to any specific region but occurred in every measured interval of the chromosome. However, right-arm intervals showed a more pronounced response than either left-arm intervals or the centromeric region. Correlated responses in sterility and distortion of transmission ratios occurred as a result of selection for male recombination. Cluster distributions of male recombinants suggested a mixture of meiotic and late gonial events but relative map distances more closely resembled those of the salivary chromosome than standard meiotic or mitotic distances. Patterns of male recombination over time in both second and third chromosomes strongly suggested a major effect associated with the presence of third chromosomes from the Harwich strain. Evidence was also found for modifiers with relatively small effects located in other regions of the genome. The overall results are interpreted in terms of a two-component model of hybrid dysgenesis.

scholarly journals Studies on the Scutellar Bristles of Drosophila melanogaster. IV. Selection for Low Bristle Number in Oregon-RC Wild-type Lines

1984 ◽  
Vol 37 (4) ◽  
pp. 277
Author(s):  
BL Sheldon ◽  
M K Evans
Keyword(s):  
Recessive Gene ◽  
Population Level ◽  
Initial Response ◽  
The Other ◽  
Selection Line ◽  
Base Population ◽  
Wild Type ◽  
Threshold Phenomenon ◽  
Bristle Number ◽  
Selection For

Results are presented of 130-145 generations of selection for low scutellar bristle number in four lines of D. melanogaster derived directly from an Oregon-RC wild-type stock and in one derived from an Oregon-RC line selected for low sternital bristle number. The most rapid initial response and the lowest mean scutellar bristle number ultimately reached, just below 2 bristles, occurred in a line in which the response was due to a new recessive gene located at approximately 17�4 on the X chromosome. Three of the other four lines reached a plateau just above a mean of 2 bristles after different patterns of response. These plateaux reflected a new canalization or threshold phenomenon at 2 bristles in these lines. The remaining line reached a mean of about 2� 5 bristles after some 50 generations and remained at that level or slightly higher thereafter, but had no indication of canalization at 2 bristles. Two relaxed lines were derived from each selection line at different times and showed variable patterns of regression towards the base population level.

scholarly journals The effect of suppressing crossing-over on the response to selection in Drosophila melanogaster

1970 ◽  
Vol 16 (1) ◽  
pp. 1-16 ◽  
Author(s):  
C. P. McPhee ◽  
Alan Robertson
Keyword(s):  
Drosophila Melanogaster ◽  
Dominant Gene ◽  
Crossing Over ◽  
Linkage Equilibrium ◽  
Selection Experiment ◽  
Base Population ◽  
Response To Selection ◽  
Wild Type ◽  
Segregation Ratios

SUMMARYA selection experiment for sternopleural bristles in Drosophila melanogaster was undertaken to measure the effect of suppressing crossing-over on chromosomes II and III using the inversions Curly and Moiré marked with a dominant gene, which severely reduce crossing-over. In one set of lines selected wild-type males were mated to selected females, heterozygous for Cy and Mé, and in a parallel set selected males carrying the inversions were mated to selected wild-type females. Because there is no crossing-over in the males in this species, crossing-over is much reduced in the first set and is at its usual level in the second. The effect of the selection was measured on flies which did not carry the inversions. The suppression of crossing-over reduced the advance at the limit by 28 ± 8% for selection upwards and by 22 ± 7% for selection downwards. The segregation ratios of the inversions were observed throughout the experiment. At the end, the proportion of wild-type flies emerging was not different in the two sets of lines. The results are consistent with an assumption of initial linkage equilibrium between loci affecting sternopleural bristles in the base population.

scholarly journals THE ORGANIZATION OF GENETIC VARIATION FOR RECOMBINATION IN DROSOPHILA MELANOGASTER

Genetics ◽  
1986 ◽  
Vol 114 (2) ◽  
pp. 525-547
Author(s):  
Lisa D Brooks ◽  
R William Marks
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Natural Population ◽  
Small Region ◽  
Crossing Over ◽  
Fine Scale ◽  
Response To Selection ◽  
Natural Genetic Variation ◽  
The Third ◽  
Scale Response

ABSTRACT The amount and form of natural genetic variation for recombination were studied in six lines for which second chromosomes were extracted from a natural population of Drosophila melanogaster. Multiply marked second, Χ and third chromosomes were used to score recombination. Recombination in the second chromosomes varied in both amount and distribution. These second chromosomes caused variation in the amount and distribution of crossing over in the Χ chromosome and also caused variation in the amount, but not the distribution, of crossing over in the third chromosome. The total amount of crossing over on a chromosome varied by 12-14%. One small region varied twofold; other regions varied by 16-38%. Lines with less crossing over on one chromosome generally had less crossing over on other chromosomes, the opposite of the standard interchromosomal effect. These results show that modifiers of recombination can affect more than one chromosome, and that the variation exists for fine-scale response to selection on recombination.

scholarly journals Correlated Responses of Different scute Genotypes to Long-term Selection for Increased Abdominal Bristle Number in Drosophila melanogaster

1974 ◽  
Vol 27 (2) ◽  
pp. 205 ◽  
Author(s):  
BH Yoo
Keyword(s):  
Genetic Background ◽  
Gene Action ◽  
Regression Coefficient ◽  
Dose Effect ◽  
Base Population ◽  
Correlated Responses ◽  
Term Selection ◽  
Bristle Number ◽  
Selection For

The first dose effect of sc+ has been measured for abdominal bristle number in six replicate lines of D. melanogaster being selected upward for this character in the sc homo-and hemizygote. The within-line regression coefficient of the heterozygote on the sc homozygote showed considerable variation among the lines with a range of 0-47-1' 22, indicating the dependence of gene action on genetic background. But, on the average, the effect of sc+ was approximately additive for abdominal bristle number. From this average, the genetic correlation in the base population between the two genotypes was estimated to be considerably less than unity, which suggests some genetic variability that is dependent on the genotype of the major locus. A similar relationship was also obtained for the two male hemizygotes.

EFFECT OF SELECTION FOR GROWTH AND FOR BREAST DEVELOPMENT ON KEEL DEFECTS IN BROILERS

1962 ◽  
Vol 42 (2) ◽  
pp. 203-210 ◽  
Author(s):  
E. S. Merritt ◽  
M. Zawalsky ◽  
R. D. Crawford ◽  
S. B. Slen
Keyword(s):  
Lower Incidence ◽  
Breast Development ◽  
Base Population ◽  
Control Strain ◽  
Selected Lines ◽  
The Third ◽  
Definite Relationship ◽  
Rate Of Growth ◽  
Selection For

Data from the third and fourth generations of a number of lines selected exclusively for growth, and of a number selected solely for breast angle, showed that selection for these traits had an effect on the incidence of crooked keels and breast blisters in 63-day-old broilers. The base population of these selected lines was a meat-control strain and a sample of this strain was reared with each hatch of the selected lines.Lines selected for growth had the highest incidence of both crooked keels and breast blisters. The lines selected for breast angle had a lower incidence of these defects than the controls, even though they did not differ from the controls in 63-day weight. It was concluded that there is a definite relationship between rate of growth, breast development and the incidence of keel defects. Market grading data on a sample of birds from these lines reflected these differences in keel defects. The market grades for conformation were lowest in the growth lines and highest in the breast lines.

scholarly journals Disruptive selection on sternopleural chaeta number in Drosophila melanogaster

1967 ◽  
Vol 9 (1) ◽  
pp. 115-118 ◽  
Author(s):  
W. Scharloo ◽  
M. Den Boer ◽  
M. S. Hoogmoed
Keyword(s):  
Drosophila Melanogaster ◽  
Sympatric Speciation ◽  
Disruptive Selection ◽  
Base Population ◽  
Geographical Isolation ◽  
Theoretical Possibility ◽  
Mendelian Population ◽  
Heterogeneous Habitat ◽  
Selection For ◽  
Partial Isolation

It is generally accepted that reproductive isolation leading to the irreversible division of a Mendelian population into two species must be initiated during a period of geographical isolation (see Mayr, 1963). Thoday & Gibson (1962, Gibson & Thoday, 1963) obtained partial isolation within a population of Drosophila melanogaster by artificial disruptive selection for the number of sternopleural chaetae. This occurred in two experiments from the same base population after seven and twelve generations respectively. On the strength of these results they concluded that speciation does not require geographical isolation and that sympatric speciation by disruptive selection in a heterogeneous habitat is at least a theoretical possibility.

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