scholarly journals Effectiveness of Regular Cycles of Intermittent Artificial Selection for A Quantitative Character in Drosophila Melanogaster

1968 ◽  
Vol 21 (6) ◽  
pp. 1187 ◽  
Author(s):  
KA Rathie ◽  
JSF Barker
Keyword(s):  
Drosophila Melanogaster ◽  
Artificial Selection ◽  
Abdominal Segment ◽  
Continuous Selection ◽  
Quantitative Character ◽  
Mass Selection ◽  
Selection Intensity ◽  
Bristle Number ◽  
Continuous Mass ◽  
Selection For

Regular cycles of intermittent mass selection have been compared with continuous mass selection at the same selection intensity for the quantitative trait of bristle number on one abdominal segment in a non-inbred strain of Drosophila melanogaster. All lines had 20 pairs of parents per generation. There were four replicates of each intermittent selection treatment, six of continuous selection at 20% selection intensity, and two at 10% selection intensity.

scholarly journals A SIMULATION STUDY OF TRUNCATION SELECTION FOR A QUANTITATIVE TRAIT OPPOSED BY NATURAL SELECTION

Genetics ◽  
1980 ◽  
Vol 94 (4) ◽  
pp. 989-1000
Author(s):  
Francis Minvielle
Keyword(s):  
Natural Selection ◽  
Artificial Selection ◽  
Random Mating ◽  
Selection Response ◽  
Quantitative Character ◽  
Mass Selection ◽  
Frequency Selection ◽  
Selection Experiments ◽  
Selection For ◽  
Selective Process

ABSTRACT A quantitative character controlled at one locus with two alleles was submitted to artificial (mass) selection and to three modes of opposing natural selection (directional selection, overdominance and underdominance) in a large random-mating population. The selection response and the limits of the selective process were studied by deterministic simulation. The lifetime of the process was generally between 20 and 100 generations and did not appear to depend on the mode of natural selection. However, depending on the values of the parameters (initial gene frequency, selection intensity, ratio of the effect of the gene to the environmental standard deviation, fitness values) the following outcomes of selection were observed: fixation of the allele favored by artificial selection, stable nontrivial equilibrium, unstable equilibrium and loss of the allele favored by artificial selection. Finally, the results of the simulation were compared to the results of selection experiments.

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).

scholarly journals Effects of Artificial Selection on Rates of Inbreeding in Populations of Drosophila Melanogaster

1969 ◽  
Vol 22 (1) ◽  
pp. 157 ◽  
Author(s):  
LP Jones
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Population Size ◽  
Effective Population Size ◽  
Artificial Selection ◽  
Selection Intensity ◽  
Base Population ◽  
Next Generation ◽  
Effective Population ◽  
Bristle Number

Three lines from the Canberra base population were selected for increased abdominal bristle number for up to 28 generations with 10 pairs of parents and 20% selection intensity. The effective population size as measured by either variance of family contributions to the next generation or by the rate of inbreeding was gener-ally lowest when the lines were responding rapidly to selection. Consideration of the contributions of families in any generation to the lines five generations later showed that much of the genetic variation came from only few families in some generations.

scholarly journals Studies in Artificial Selection of Quantitative Characters I. Selection for Abdominal Bristles in Drosophila Melanogaster

1963 ◽  
Vol 16 (2) ◽  
pp. 490 ◽  
Author(s):  
BL Sheldon
Keyword(s):  
Drosophila Melanogaster ◽  
Artificial Selection ◽  
Mass Selection ◽  
Wild Type ◽  
Diallel Crosses ◽  
Laboratory Stock ◽  
Quantitative Characters ◽  
Selection For ◽  
Selection Of

Genetic and phenotypic parameters for number of abdominal bristles were estimated from diallel crosses in a wild-type laboratory stock, Oregon-Reo Two replicate mass selection lines in both high and low directions were developed and run for over 30 generations. The same parameters were estimated from dianel ~rosses at intervals during the experiment.

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