Long-term selection for a quantitative character in large replicate populations of Drosophila melanogaster

1980 ◽  
Vol 57 (3) ◽  
pp. 113-117 ◽  
Author(s):  
B. H. Yoo ◽  
F. W. Nicholas ◽  
K. A. Rathie
Keyword(s):  
Drosophila Melanogaster ◽  
Quantitative Character ◽  
Term Selection ◽  
Selection For

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 Long-term selection for a quantitative character in large replicate populations ofDrosophila melanogaster: II. Lethals and visible mutants with large effects

1980 ◽  
Vol 35 (1) ◽  
pp. 19-31 ◽  
Author(s):  
B. H. Yoo
Keyword(s):  
Drosophila Melanogaster ◽  
Mutation Rate ◽  
Quantitative Character ◽  
Frequency Of Occurrence ◽  
Term Selection ◽  
Bristle Number ◽  
Selection For ◽  
First Time ◽  
G 14

SUMMARYLethal frequencies on the second and third chromosomes were estimated three times in six replicate lines ofDrosophila melanogasterselected for increased abdominal bristle number, at G 14–16, G 37–44 and G 79. Ten lethals were detected at a frequency of about 5% or higher at G 14–16, of which only one recurred in subsequent tests. Another ten lethals which had not been detected previously were found at G 37–44, and the 5 most frequent ones recurred at G 79. In the last test, 15 presumably new lethals were detected, of which at least 4 appeared well established. In addition, six reversions (fromsctosc+), a new mutant at the scute locus andscawere discovered. The effects on the selected character of some lethals and visible mutants were large and variable, but not always sufficient to explain the observed frequencies. The major lethals detected at G 37–44 and G 79 for the first time were most probably ‘mutations’ (in the broad sense) which occurred during selection. The likely origins of such ‘mutations’ were discussed, with a suggestion that the known mutation rate for recessive lethals would not be incompatible with the observed frequency of occurrence of the ‘mutations’.

scholarly journals Long-Term Selection for a Quantitative Character in Large Replicate Populations of Drosophila Melanogaster. V. The Inbreeding Effect of Selection

1980 ◽  
Vol 33 (6) ◽  
pp. 713 ◽  
Author(s):  
BH Yoo
Keyword(s):  
Drosophila Melanogaster ◽  
Quantitative Character ◽  
Relaxed Selection ◽  
Term Selection ◽  
Bristle Number ◽  
Selection For

Four replicate lines of D. melanogaster, which had been selected for increased abdominal bristle number for 58 or 69 generations, were pedigreed for nine generations under selection with or without replacements for failed matings (SW and SO sublines) and under relaxed selection also with or without replacements (RW and RO sublines).

SELECTION FOR MALATHION-RESISTANCE IN DROSOPHILA MELANOGASTER

1981 ◽  
Vol 23 (2) ◽  
pp. 355-369 ◽  
Author(s):  
R. S. Singh ◽  
R. A. Morton
Keyword(s):  
Drosophila Melanogaster ◽  
Selection Procedure ◽  
Dominant Trait ◽  
Lower Intensity ◽  
Term Selection ◽  
Modification Factor ◽  
Polygenic System ◽  
Selection For ◽  
High Selection

Results from a long-term selection experiment for malathion-resistance in Drosophila melanogaster are described. A pooled population of 40 locally-caught, iso-female lines was exposed to increasing concentrations of malathion in the food at both a high selection intensity (MH) and a lower intensity (ML). The response was consistent with a polygenic system. Both adult and larval resistance increased in parallel. Changes in the dose-response curve of adults could be approximately described by a dose-modification factor. Larval resistance was more complex; both selected populations showed a maternal effect which could not be explained by sex-linked genes. Larval resistance in the selected populations behaved as a co-dominant trait with respect to the susceptible controls. Adult resistance was dominant in the ML and co-dominant in the MH population, suggesting that different genes conferring resistance were selected. The selection procedure also produced a developmental delay in both populations, dependent on malathion concentration, but present even in its absence.

scholarly journals Studies on the Scutellar Bristles of Drosophila Melanogaster ID. Long-Term Selection for High Bristle Number in Three further Lines Derived From the Oregon-RC Strain, Correlated Responses in Abdominal Bristles, lUld Changes in Regulation of the Scute Locu

1981 ◽  
Vol 34 (3) ◽  
pp. 347
Author(s):  
BL Sheldon ◽  
M K Evanst
Keyword(s):  
Sex Differences ◽  
Drosophila Melanogaster ◽  
Correlated Response ◽  
Correlated Responses ◽  
Term Selection ◽  
Bristle Number ◽  
Selection For

Results of selection over 135 generations for high scutellar bristle number in three further lines derived from Oregon-RC complement those on the four lines reported previously (Sheldon and Milton 1972). All lines differed widely in pattern of scutellar response, correlated response in abdominal and posterior central scutellar bristles, sex differences, and behaviour on relaxing selection, though the selection limits reached in the present three lines were lower than in the previous lines.

Long-Term Selection for Pupal Weight in Tribolium castaneum

2010 ◽  
pp. 211-224
Author(s):  
W. M. Muir ◽  
D. Miles ◽  
A. E. Bell
Keyword(s):  
Tribolium Castaneum ◽  
Pupal Weight ◽  
Term Selection ◽  
Selection For

scholarly journals Optimum selection intensities in artificial selection programmes: an experimental evaluation

1977 ◽  
Vol 30 (2) ◽  
pp. 115-119 ◽  
Author(s):  
R. Frankham
Keyword(s):  
Experimental Evaluation ◽  
Selection Intensity ◽  
Effective Population ◽  
Term Selection ◽  
Optimum Selection ◽  
Selection For ◽  
Selection Intensities ◽  
Selection Of ◽  
Better Than

SUMMARYAn experimental evaluation of Robertson's (1970) theory concerning optimum intensities of selection for selection of varying durations has been carried out using published results from a long term selection study in Drosophila. Agreement of predicted rankings of treatments with expectations was excellent for low values of t/T (generations/total number scored) but poor for larger values of t/T. This was due to the 20% selection intensity treatments responding worse than expected and the 40% treatments relatively better than expected. Several possible reasons for the discrepancies exist but the most likely explanation is considered to be the greater reduction in effective population size due to selection in treatments with more intense selection.

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