STUDIES ON NATURAL POPULATIONS OF DROSOPHILA. XII. HETEROSIS AND FITNESS CHARACTERS IN HYBRIDS BETWEEN DIFFERENT POPULATIONS OF DROSOPHILA MELANOGASTER

1970 ◽  
Vol 12 (4) ◽  
pp. 695-710 ◽  
Author(s):  
A. O. Tantawy ◽  
M. R. El-Helw
Keyword(s):  
Drosophila Melanogaster ◽  
Inbred Line ◽  
Egg Production ◽  
Natural Populations ◽  
Relative Fitness ◽  
Environment Interaction ◽  
Population Variance ◽  
Genotype Environment Interaction ◽  
The Poor ◽  
Different Populations

Three different unrelated natural populations of Drosophila melanogaster from Scotland, Japan and Egypt, as well a highly inbred line, were the basis of the present study. Crosses were made within and between natural populations and between each of the natural populations and the highly inbred line to obtain the parental, F1 and F2 generations and their relative fitness studied at 15°, 25° and 28 °C.The F1 interpopulation hybrids were superior to both parents in egg production, percentage emergence and longevity of adults in most of the crosses. Heterosis tended to be higher at 15° and 28° than at 25 °C. The F2 in all crosses was inferior to the F1 and also inferior to one or both parents. In crossing the inbred line with any of the natural populations, the F1 generally showed higher heterosis than that of the interpopulation hybrids; the F2 was also inferior to the F1 but superior to the inbred parent.Significant genotype-environment interaction was detected, indicating the differences in sensitivity to temperature in each population. Variance of any-given fitness character of a superior population at a given temperature was often smaller than the poor genotype. There was a decline in the coefficient of variation in the F1 generation and an increase in the F2's.

Genetic Variation and Causes of Genotype-Environment Interaction in the Body Size of Blue Tit (Parus caeruleus)

Genetics ◽  
1998 ◽  
Vol 148 (3) ◽  
pp. 1233-1244 ◽  
Author(s):  
Juha Merilä ◽  
James D Fry
Keyword(s):  
Genetic Variation ◽  
Body Size ◽  
Genetic Variance ◽  
Natural Populations ◽  
The Body ◽  
Environment Interaction ◽  
Parus Caeruleus ◽  
Genotype Environment Interaction ◽  
The Poor ◽  
Good Environment

Abstract In several studies of natural populations of birds, the heritability of body size estimated by parent-offspring regression has been lower when offspring have developed in poor feeding regimens than when they developed in good feeding regimens. This has led to the suggestion that adaptation under poor regimens may be constrained by lack of genetic variation. We examined the influence of environmental conditions on expression of genetic variation in body size of nestling blue tits (Parus caeruleus) by raising full sibs in artificially reduced and enlarged broods, corresponding to good and poor feeding regimens, respectively. Individuals grown in the poor regimen attained smaller body size than their sibs grown in the good regimen. However, there was among-family variation in response to the treatments—i.e., genotype-environment interactions (GEIs). Partitioning the GEI variance into contributions attributable to (1) differences in the among-family genetic variance between the treatments and (2) imperfect correlation of genotypic values across treatments identified the latter as the main cause of the GEI. Parent-offspring regressions were not significantly different when offspring were reared in the good environment (h2 = 0.75) vs. when they were reared in the poor environment (h2 = 0.63). Thus, there was little evidence that genetic variance in body size was lower under the poor conditions than under the good conditions. These results do not support the view that the genetic potential for adaptation to poor feeding conditions is less than that for adaptation to good conditions, but they do suggest that different genotypes may be favored under the different conditions.

scholarly journals The Genetic Structure of Natural Populations of Drosophila melanogaster. XX. Comparison of Genotype-Environment Interaction in Viability Between a Northern and a Southern Population

Genetics ◽  
1987 ◽  
Vol 117 (2) ◽  
pp. 245-254
Author(s):  
Toshiyuki Takano ◽  
Shinichi Kusakabe ◽  
Terumi Mukai
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Natural Populations ◽  
Environment Interaction ◽  
Southern Population ◽  
Genotypic Variance ◽  
Diversifying Selection ◽  
Genotype Environment Interaction ◽  
Interaction Variance

ABSTRACT In order to examine the operation of diversifying selection as the maintenance mechanism of excessive additive genetic variance for viability in southern populations in comparison with northern populations of Drosophila melanogaster, two sets of experiments were conducted using second chromosomes extracted from the Ogasawara population (a southern population in Japan) and from the Aomori population (a northern population in Japan). Chromosomal homozygote and heterozygote viabilities were estimated in eight kinds of artificially produced breeding environments. The main findings in the present investigation are as follows: (1) Significant genotype-environment interaction was observed using chromosomes extracted from the Ogasawara population. Indeed, the estimate of the genotype-environment interaction variance for heterozygotes was significantly larger than that of the genotypic variance. On the other hand, when chromosomes sampled from the Aomori population were examined, that interaction variance was significant only for homozygotes and its value was no more than one quarter of that for the chromosomes from the Ogasawara population. (2) The average genetic correlation between any two viabilities of the same lines estimated in the eight kinds of breeding environments for the chromosomes sampled from the Ogasawara population was smaller than that for the chromosomes from the Aomori population both in homozygotes and in heterozygotes, especially in the latter. (3) The stability of heterozygotes over homozygotes against fluctuations of environmental conditions was seen in the chromosomes from the Ogasawara population, but not from the Aomori population. (4) From the excessive genotype-environment interaction variance compared with the genotypic variance in heterozygotes, it was suggested for the chromosomes from the Ogasawara population that the reversal of viability order between homozygotes took place in some environments at the locus level. On the basis of these findings, it is strongly suggested that diversifying selection is operating in a southern population of D. melanogaster on some of the viability polygenes which are probably located outside the structural loci, and the excessive additive genetic variance of viability in southern populations is maintained by this type of selection.

THE GENETIC STRUCTURE OF NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER. XIX. GENOTYPE-ENVIRONMENT INTERACTION IN VIABILITY

Genetics ◽  
1985 ◽  
Vol 111 (1) ◽  
pp. 43-55
Author(s):  
Hidenori Tachida ◽  
Terumi Mukai
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variance ◽  
Culture Media ◽  
Additive Genetic Variance ◽  
Natural Populations ◽  
Environment Interaction ◽  
Diversifying Selection ◽  
Genotype Environment Interaction ◽  
Significant Difference ◽  
Experimental Findings

ABSTRACT To investigate whether or not an excess of additive genetic variance for viability detected in southern natural populations of Drosophila melanogaster was created by diversifying selection, genotype-environment interaction was tested as follows. (1) Two karyotype chromosomes were used: 61 second chromosomes with the standard karyotype and 63 second chromosomes carrying In(2L)t. Their homozygote viabilities were larger than 50% of the average viability of random heterozygotes. (2) The effects of two factors (culture media and yeasts) were examined at three levels (the culture media: tomato, corn and banana; and the yeasts: sake, brewer's and baker's). The results of 16 three by three factorial experiments by the Cy method in the same karyotype groups for relative viabilities of homozygotes and heterozygotes elucidated the following findings: (1) there was no significant difference between the two karyotype groups, (2) the variance components of genotype-environment interaction were highly significant, (3) the variance component of heterozygotes was significantly smaller than that of homozygotes. From the experimental findings and previous results, diversifying selection in natural populations acting on viability polygenes to increase the additive genetic variance was suggested. The relation of the present result to protein polymorphism is also discussed.

scholarly journals QTL mapping of genotype–environment interaction for fitness in Drosophila melanogaster

1998 ◽  
Vol 71 (2) ◽  
pp. 133-141 ◽  
Author(s):  
JAMES D. FRY ◽  
SERGEY V. NUZHDIN ◽  
ELENA G. PASYUKOVA ◽  
TRUDY F. C. MACKAY
Keyword(s):  
Environmental Heterogeneity ◽  
Natural Populations ◽  
Antagonistic Pleiotropy ◽  
Environment Interaction ◽  
Standard Medium ◽  
Fitness Effects ◽  
Genotype Environment Interaction ◽  
Different Temperatures ◽  
Temperature Interaction ◽  
Ri Lines

A fundamental assumption of models for the maintenance of genetic variation by environmental heterogeneity is that selection favours alternative alleles in different environments. It is not clear, however, whether such antagonistic pleiotropy is common. We mapped quantitative trait loci (QTLs) causing variation for reproductive performance in each of three environmental treatments among a set of 98 recombinant inbred (RI) lines derived from a cross between two D. melanogaster laboratory strains. The three treatments were standard medium at 25°C, ethanol-supplemented medium at 25°C, and standard medium at 18°C. The RI lines showed highly significant genotype–environment interaction for the fitness measure. Of six QTLs with significant effects on fitness in at least one of the environments, five had significantly different effects at the different temperatures. In each case, the QTL by temperature interaction arose because the QTL had stronger effects at one temperature than at the other. No evidence for QTLs with opposite fitness effects in different environments was found. These results, together with those of recent studies of crop plants, suggest that antagonistic pleiotropy is a relatively uncommon form of genotype–environment interaction for fitness, but additional studies of natural populations are needed to confirm this conclusion.

scholarly journals Temporal uniformity of the spontaneous mutational variance of quantitative traits in Drosophila melanogaster

2000 ◽  
Vol 75 (1) ◽  
pp. 47-51 ◽  
Author(s):  
AURORA GARCÍA-DORADO ◽  
JESUS FERNÁNDEZ ◽  
CARLOS LÓPEZ-FANJUL
Keyword(s):  
Drosophila Melanogaster ◽  
Morphological Traits ◽  
Quantitative Traits ◽  
Wing Length ◽  
Environment Interaction ◽  
Genotype Environment Interaction ◽  
Bristle Number ◽  
Sib Mating ◽  
Mutational Variance ◽  
Interaction Variance

Spontaneous mutations were allowed to accumulate over 209 generations in more than 100 lines, all of them independently derived from a completely homozygous population of Drosophila melanogaster and subsequently maintained under strong inbreeding (equivalent to full-sib mating). Traits scored were: abdominal (AB) and sternopleural (ST) bristle number, wing length (WL) and egg-to-adult viability (V). On two occasions – early (generations 93–122) and late (generations 169–209) – ANOVA estimates of the mutational variance and the mutational line × generation interaction variance were obtained. Mutational heritabilities of morphological traits ranged from 2 × 10−4 to 2 × 10−3 and the mutational coefficient of variation of viability was 0·01. For AB, WL and V, temporal uniformity of the mutational variance was observed. However, a fluctuation of the mutational heritability of ST was detected and could be ascribed to random genotype × environment interaction.

scholarly journals Properties of spontaneous mutations affecting quantitative traits

1999 ◽  
Vol 74 (3) ◽  
pp. 341-350 ◽  
Author(s):  
A. GARCÍA-DORADO ◽  
C. LÓPEZ-FANJUL ◽  
A. CABALLERO
Keyword(s):  
Deleterious Mutation ◽  
Natural Populations ◽  
Detectable Effect ◽  
Environment Interaction ◽  
Fitness Component ◽  
Standing Variation ◽  
Genotype Environment Interaction ◽  
Component Traits ◽  
Mutational Variance ◽  
New Mutations

Recent mutation accumulation results from invertebrate species suggest that mild deleterious mutation is far less frequent than previously thought, implying smaller expressed mutational loads. Although the rate (λ) and effect (s) of very slight deleterious mutation remain unknown, most mutational fitness decline would come from moderately deleterious mutation (s ≈ 0·2, λ ≈ 0·03), and this situation would not qualitatively change in harsh environments. Estimates of the average coefficient of dominance (h¯) of non-severe deleterious mutations are controversial. The typical value of h¯ = 0·4 can be questioned, and a lower estimate (about 0·1) is suggested. Estimated mutational parameters are remarkably alike for morphological and fitness component traits (excluding lethals), indicating low mutation rates and moderate mutational effects, with a distribution generally showing strong negative asymmetry and little leptokurtosis. New mutations showed considerable genotype–environment interaction. However, the mutational variance of fitness-component traits due to non-severe detrimental mutations did not increase with environmental harshness. For morphological traits, a class of predominantly additive mutations with no detectable effect on fitness and relatively small effect on the trait was identified. This should be close to that responsible for standing variation in natural populations.

scholarly journals Experimental modification of the dominance relations of a melanotic tumour gene in Drosophila melanogaster

1972 ◽  
Vol 20 (1) ◽  
pp. 115-135 ◽  
Author(s):  
Ann Louise Belt ◽  
Barrie Burnet
Keyword(s):  
Drosophila Melanogaster ◽  
Larval Instar ◽  
Environment Interaction ◽  
Larval Food ◽  
Dominance Relations ◽  
The Third ◽  
Genotype Environment Interaction ◽  
Tumour Formation ◽  
Food Medium ◽  
Melanotic Tumour

SUMMARYThe melanotic tumour gene tu-C4 in Drosophila melanogaster shows incomplete dominance, together with variable penetrance and expressivity. It is tentatively located in the region of locus 52–53 on the third chromosome. Tumour formation in mutant homozygotes involves a precocious haemocyte transformation leading to the appearance of lamellocytes at the beginning of the third larval instar. These aggregate to form tumour-like masses which subsequently melanize. The process of tumour formation is in broad outline similar to that found in other tumour strains. Melanotic tumour formation is treated as a dichotomous threshold character, assuming an underlying normal distribution of liability relative to a fixed threshold. The expression of the tumour gene can be influenced by the levels of protein, phospholipid, nucleic acid and carbohydrate in the larval food medium, and changes in dominance and penetrance induced by sub-optimal environments deficient in these nutrients are positively correlated. Reinforcement by selection of the dominance relations of tu-C4 was accompanied by correlated changes in penetrance. Conversely, selection for increased penetrance was accompanied by correlated changes in dominance. Dominance and penetrance, it is concluded, are fundamentally related aspects of tumour gene expression. Recruitment of dominance modifiers linked to the tumour gene was excluded by the mating scheme employed, and the observed changes in dominance relations in response to selection were due largely to modifiers located on the second chromosome. Changes in dominance relations produced by selection could be significantly reinforced, or reversed, by environmental factors and consequently show a substantial genotype – environment interaction effect. These facts are relevant to current theories of dominance evolution.

scholarly journals Genotype-Environment Interaction at Quantitative Trait Loci Affecting Sensory Bristle Number in Drosophila melanogaster

Genetics ◽  
1998 ◽  
Vol 149 (4) ◽  
pp. 1883-1898 ◽  
Author(s):  
Marjorie C Gurganus ◽  
James D Fry ◽  
Sergey V Nuzhdin ◽  
Elena G Pasyukova ◽  
Richard F Lyman ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Quantitative Trait Loci ◽  
Quantitative Trait ◽  
Rank Order ◽  
Recombinant Inbred Lines ◽  
Environment Interaction ◽  
Genotype Environment Interaction ◽  
Bristle Number ◽  
A Genome ◽  
Trait Loci

AbstractThe magnitude of segregating variation for bristle number in Drosophila melanogaster exceeds that predicted from models of mutation-selection balance. To evaluate the hypothesis that genotype-environment interaction (GEI) maintains variation for bristle number in nature, we quantified the extent of GEI for abdominal and sternopleural bristles among 98 recombinant inbred lines, derived from two homozygous laboratory strains, in three temperature environments. There was considerable GEI for both bristle traits, which was mainly attributable to changes in rank order of line means. We conducted a genome-wide screen for quantitative trait loci (QTLs) affecting bristle number in each sex and temperature environment, using a dense (3.2-cM) marker map of polymorphic insertion sites of roo transposable elements. Nine sternopleural and 11 abdominal bristle number QTLs were detected. Significant GEI was exhibited by 14 QTLs, but there was heterogeneity among QTLs in their sensitivity to thermal and sexual environments. To further evaluate the hypothesis that GEI maintains variation for bristle number, we require estimates of allelic effects across environments at genetic loci affecting the traits. This level of resolution may be achievable for Drosophila bristle number because candidate loci affecting bristle development often map to the same location as bristle number QTLs.

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