scholarly journals Genetic differences between populations of Drosophila melanogaster for a quantitative trait: I. Laboratory populations

1973 ◽  
Vol 22 (1) ◽  
pp. 51-68 ◽  
Author(s):  
C. López-Fanjul ◽  
W. G. Hill
Keyword(s):  
Drosophila Melanogaster ◽  
Gene Frequency ◽  
Total Response ◽  
Selected Lines ◽  
Synthetic Populations ◽  
Bristle Number ◽  
Laboratory Populations ◽  
Selection For ◽  
Different Origins ◽  
Two Populations

SUMMARYAn experiment was carried out to test whether two laboratory cage populations of Drosophila melanogaster from different origins (Kaduna and Pacific) differed in the genes for sternopleural bristle number. The means, variances and heritabilities of the two populations and the synthetic formed from crosses between them were very similar.Selection for low bristle number was practised in small replicate lines, six of each pure population and nine of the synthetic. On average, Pacific responded to selection rather more rapidly than either Kaduna or the synthetic, but there was little difference in the limit achieved.Crosses between replicates within populations were made and selection continued, and these lines subsequently crossed between populations and reselected. Additional response was obtained by this procedure but the crosses between the replicates of the pure and synthetic populations attained similar selection limits.An analysis of effects of individual chromosomes from the selected lines on bristle number indicated that the contribution of each chromosome to total response was about the same in Pacific, Kaduna and the synthetic.It is concluded that differences in gene frequency, rather than the presence or absence of particular alleles, are mainly responsible for the differences observed between the populations.

scholarly journals Long-term selection for a quantitative character in large replicate populations of Drosophila melanogaster: 1. Response to selection

1980 ◽  
Vol 35 (1) ◽  
pp. 1-17 ◽  
Author(s):  
B. H. Yoo
Keyword(s):  
Drosophila Melanogaster ◽  
Phenotypic Variability ◽  
Selection Response ◽  
Quantitative Character ◽  
Response Patterns ◽  
Total Response ◽  
Term Selection ◽  
Bristle Number ◽  
Selection For

SUMMARYThe response to long-term selection for increased abdominal bristle number was studied in six replicate lines of Drosophila melanogaster derived from the sc Canberra outbred strain. Each line was continued for 86–89 generations with 50 pairs of parents selected at an intensity of 20%, and subsequently for 32–35 generations without selection. Response continued for at least 75 generations and average total response was in excess of 36 additive genetic standard deviations of the base population (σA) or 51 times the response in the first generation. The pattern of longterm response was diverse and unpredictable typically with one or more accelerated responses in later generations. At termination of the selection, most of the replicate lines were extremely unstable with high phenotypic variability, and lost much of their genetic gains rapidly upon relaxation of selection.The variation in response among replicates rose in the early phase of selection to level off at approximately 7·6 around generation 25. As some lines plateaued, it increased further to a level higher than would be accommodated by most genetic models. The replicate variation was even higher after many generations of relaxed selection. The genetic diversity among replicates, as revealed in total response, the individuality of response patterns and variation of the sex-dimorphism ratio, suggests that abdominal bristle number is influenced potentially by a large number of genes, but a smaller subset of them was responsible for selection response in any one line.

scholarly journals Selection for Ethanol Tolerance in Two Populations of Drosophila Melanogaster Segregating Alcohol Dehydrogenase Allozymes

1979 ◽  
Vol 32 (3) ◽  
pp. 387 ◽  
Author(s):  
John B Gibson ◽  
NigeI Lewis ◽  
MichaeI Adena ◽  
Susan R Wilson
Keyword(s):  
Drosophila Melanogaster ◽  
Alcohol Dehydrogenase ◽  
Ethanol Tolerance ◽  
Selection For ◽  
Two Populations

Selection for ethanol tolerance was equally successful in two populations of D. melanogaster in both of which the frequency of AdhF was 0�5 at the start of the experiment.

scholarly journals Optimum selection strategies: studies with Drosophila melanogaster

1985 ◽  
Vol 46 (1) ◽  
pp. 101-105
Author(s):  
Aurora García-Dorado ◽  
Carlos López-Fanjul
Keyword(s):  
Drosophila Melanogaster ◽  
Theoretical Treatment ◽  
Good Qualitative Agreement ◽  
Selected Lines ◽  
Selection Strategies ◽  
Bristle Number ◽  
Optimum Selection ◽  
Different Types ◽  
Males And Females ◽  
Number Of Individuals

SUMMARYAn experimental evaluation of Jódar & López-Fanjul's (1977) theoretical treatment of the optimum proportions to select when the numbers of males and females scored are unequal has been carried out for sternopleural bristle number in Drosophila melanogaster. Three different values of the sex-ratio (c) were considered (c = 1, 4 and 10) for the same total number of individuals scored per generation. For each c value two types of line were selected with proportions theoretically maximizing the response to be attained after 10 or 20 generations, respectively. Thus, there were six types of lines and each type was replicated sixfold. A good qualitative agreement was found between the observed and the expected rankings of the different types of selected lines at the designated generations.

scholarly journals Studies on The Scutellar Bristles of Drosophila Melanogaster I. Basic Variability, Some Temperature and Culture Effects, and Responses to Short-Term Selection in the Oregon-Rc Strain

1968 ◽  
Vol 21 (4) ◽  
pp. 721 ◽  
Author(s):  
BL Sheldon
Keyword(s):  
Drosophila Melanogaster ◽  
Major Gene ◽  
Selection Response ◽  
Wild Type ◽  
Short Term ◽  
Term Selection ◽  
Bristle Number ◽  
Selection For ◽  
High Selection ◽  
Culture Effects

The results of short runs of disruptive and high selection for scutellar bristles in wild-type Drosophila are explained in terms of the hypothesis that canalization at four bristles is due to regulation of the major gene in the developmental system (Rendel, Sheldon, and Finlay 1965). Selection response has probably been due to selection for modifier (minor) genes rather than for isoalleles of the major gene or weak regulator alleles. Some environmental effects on the character, short runs of selection for low bristle number or different bristle types, and effects of relaxing selection are also reported.

Aerial performance of Drosophila melanogaster from populations selected for upwind flight ability.

1997 ◽  
Vol 200 (21) ◽  
pp. 2747-2755 ◽  
Author(s):  
J H Marden ◽  
M R Wolf ◽  
K E Weber
Keyword(s):  
Drosophila Melanogaster ◽  
Vertical Velocity ◽  
Three Dimensional ◽  
Selected Lines ◽  
Flight Ability ◽  
Performance Levels ◽  
Flight Velocity ◽  
Upwind Flight ◽  
Maximal Performance ◽  
Selection For

A computerized system for three-dimensional tracking of large numbers of individual free-flying insects was used to assess the performance of Drosophila melanogaster from populations that had undergone 160 generations of selection for upwind flight ability. Compared with control lines, the selected lines showed significant increases in mean flight velocity, decreases in angular trajectory and a significant change in the interaction between velocity and angular trajectory. Maximal flight velocity was apparent as a sharply defined upper boundary of the distribution of horizontal and vertical velocity as a function of angular trajectory; this upper bound (0.85 ms-1) differed little between the selected and control lines, although individuals from the selected lines attained maximal performance levels much more frequently. Maximum induced power output was calculated directly from the product of maximum vertical velocity and body weight. This measure (28 W kg-1 muscle) was closely predicted by a scaling relationship derived from the load-lifting limits of larger insects and vertebrates, as well as tethered D. melanogaster stimulated via their optomotor reflex to produce maximal lift. These results indicate that selection for flight performance can readily alter the relative effort and/or the frequency of phenotypes capable of attaining population-wise maximal performance levels, but shows little ability to increase population-wise maximal performance.

scholarly journals Decanalization of scutellar bristle number in Drosophila

1971 ◽  
Vol 17 (2) ◽  
pp. 95-101 ◽  
Author(s):  
W. R. Scowcroft ◽  
B. D. H. Latter
Keyword(s):  
Marked Reduction ◽  
Test System ◽  
Developmental Stability ◽  
Base Population ◽  
Wild Type ◽  
X Ray ◽  
Bristle Number ◽  
Selection For ◽  
Two Populations

SUMMARYA major difference in developmental stability has been demonstrated between two populations produced by artificial selection for supernumerary scutellar bristles. The test system involves the substitution of an X-ray induced partial revertant of sc1 for the wild-type allele at the scute locus, enabling direct comparisons to be made of the degree of canalization at the wild-type level of expression of the character. One population is comparable with the unselected Canberra stock in stability, though it differs appreciably in mean bristle number: the other population shows a marked reduction in the level of regulation of bristle number variability. The alleles responsible for the reduced level of canalization are rare in the base population, and are of particular importance in the determination of limits to directional selection. Their effects on developmental stability have been shown to depend on the activity of the allele at the scute locus.

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