Doubling Dose for Polygenic Mutations in &lt;i&gt;Drosophila&lt;/i&gt; &lt;i&gt;melanogaster&lt;/i&gt;

Yamada, Yukio; Kitagawa, Osamu

doi:10.1266/jjg.36.76

Cited by 14 publications

(14 citation statements)

References 7 publications

(9 reference statements)

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“…Robertson (1955) considered that most genes affecting abdominal bristle number had no direct effect on reproductive fitness. Yamada and Kitagawa (1961) and Tobari and Nei (1965) agreed, because X-irradiation increased the phenotypic variance of abdominal bristle number, but had no effect on the mean. Perhaps of more relevance to our results is the study of Latter (1963) on abdominal bristle number in this same Canberra population.…”

Section: Discussionmentioning

confidence: 78%

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

Rathie¹,

Barker²

1968

Aust. Jnl. Of Bio. Sci.

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SummaryRegular 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.In the treatment designations, the numbers of selected and non-selected generations per cycle are given first and second respectively, separated by a colon. The intermittent selection treatments, with number of generations of actual selection in parentheses, were 1:3 (5) and 1:1 (17) at 10% selection intensity, and 3:1 (24) and 6:2 (24) at 20% selection intensity. Rates of response of all treatments except 1:3 had declined by the time they were terminated, although none appeared plateaued. Sublines (continuous, 2:1, and 1:1 selection at an intensity of 20%) split off two replicates of treatment 1:1 at termination revealed little variation still available for utilization under selection in these two lines.All intermittent selection treatments gave similar amounts of response per generation of actual selection to those of the relevant continuous selection treatments.Measures of reproductive fitness, bristle number changes over five generations of relaxed selection under crowded mass culture, phenotypic variance for bristle number, and frequencies of lethal genes were obtained for almost all lines. As selection progressed, continuous selection lines were more prone to (1) exhibit increases in phenotypic variance for abdominal bristle number, and (2) have larger declines in abdominal bristle number on relaxation of selection.Although some replicates of almost all treatments showed little or no loss of reproductive fitness, fitness declined more under continuous than under intermittent selection.Failure to get increased response per generation of actual selection in the intermittent selection lines relative to their continuous selection controls may have been because responses obtained in both sets oflines were largely due to concentration of a few genes which were individually of large effect, and initially present at low frequencies. The greater decline in fitness under continuous selection suggests that linked complexes of genes deleterious to fitness and ones responsible for response in bristle number were important.

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Section: Discussionmentioning

confidence: 78%

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

Rathie¹,

Barker²

1968

Aust. Jnl. Of Bio. Sci.

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“…Taking the average increment in variance per genome, per generation due to spontaneous mutation as 0.00475, which is an average of the value for abdominal bristles reported by Clayton and Robertson (1955) and Paxman (1957), the doubling dose calculated from the results of the present experiment, when both sexes were irradiated, is 16R (Table 3). Yamada and Kitagawa (1961) Recently two papers were published in which these authors estimated the increase in variance per roentgen (Calayton and Robertson, 1964;Tobari and Nei, 1965). Estimates in the former report were much lower than ours, but the latter reported results which were slightly higher than those obtained in this experiment.…”

Section: Discussionmentioning

confidence: 99%

“…The main result of this work has already published in Yamada and Kitagawa (1961). The details of the selection experiments after irradiation is presented in this paper.…”

mentioning

confidence: 92%

THE EFFECTS OF X-RAY IRRADIATION ON SELECTION RESPONSE IN <i>ôDROSOPHILA MELANOGASTER</i>

Kitagawa

1967

The Japanese journal of genetics

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One of the most important problems in population genetics concerns how much genetic variation can be induced in the polygenic systems of various organisms by exposure to radiation, and the extent to which this variation affects the process of organic evolution. However, works dealing with spontaneous or induced mutations in polygenic systems in animals as well as in plants are rather few. Buzzati-Traverso (1953) reported in Drosophila that new variation induced by X-rays in polygenic systems can be utilized for natural selection under normal laboratory conditions. He has alsoshown that a rapid increase in fitness as measured by its main components, such as the number of eggs laid and the numbers of adult offspring, accompanies this increased mutation rate. Scossiroli (1953) reported a high efficacy of artificial selection for number of sternopleural bristles after irradiation in a strain that had previously reached a plateau under selection without irradiation. More recent works by several investigators on artificial selection for the number of bristles in Drosophila have shown more effective response under irradiation than under natural conditions Robertson, 1955, 1064;Scossiroli and Scossiroli, 1959;Tobari and Nei, 1965).The purpose of the present experiment is to clarify the mechanism by which new genetic variability available for artificial selection is induced by X-rays, and to estimate the amount of increase of polygenic variability in abdominal bristle numbers. The main result of this work has already published in Yamada and Kitagawa (1961). The details of the selection experiments after irradiation is presented in this paper. MATERIALS AND EXPERIMENTAL METHODSSelection was conducted for the total number of bristles on the fourth and fifth abdominal plates of D. melanogaster. Two strains were used as the base populations.The P strain was the isogenic Oregon-R strain. The C strain consisted of F2 flies from a cross between two isogenic strains, Oregon-R and Samarkand, each having been maintained by full-sib pair mating for several hundred generations.

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“…There is some experimental evidence that the amount of new genetic variance produced by mutation each generation is roughly constant independent of the background level of genetic variance. The data of Scossiroli & Scossiroli (1959), Yamada & Kitagawa (1961) and Clayton & Robertson (1964) show that the genetic variance produced in quantitative characters of Drosophila by a given dose of X-rays is approximately the same in lines with low and high heterozygosity. No other evidence bearing on this point was found.…”

Section: Qualitative Analysismentioning

confidence: 97%

The maintenance of genetic variability by mutation in a polygenic character with linked loci

1975

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It is assumed that a character under stabilizing selection is determined genetically by n linked, mutable loci with additive effects and a range of many possible allelic effects at each locus. A general qualitative feature of such systems is that the genetic variance for the character is independent of the linkage map of the loci, provided linkage is not very tight. A particular detailed model shows that certain aspects of the genetic system are moulded by stabilizing selection while others are selectively neutral. With reference to experimental data on characters of Drosophila flies, maize, and mice, it is concluded that large amounts of genetic variation can be maintained by mutation in polygenic characters even when there is strong stabilizing selection. The properties of the model are compared with those of heterotic models with linked loci.

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Doubling Dose for Polygenic Mutations in <i>Drosophila</i> <i>melanogaster</i>

Cited by 14 publications

References 7 publications

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

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

THE EFFECTS OF X-RAY IRRADIATION ON SELECTION RESPONSE IN <i>ôDROSOPHILA MELANOGASTER</i>

The maintenance of genetic variability by mutation in a polygenic character with linked loci

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