scholarly journals The Genotypic Control of Longevity in Drosophila Melanogaster Under Two Environmental Regimes

1966 ◽  
Vol 19 (4) ◽  
pp. 587 ◽  
Author(s):  
PA Parsons
Keyword(s):  
Drosophila Melanogaster ◽  
Inbred Strains ◽  
Environmental Regimes ◽  
Two Temperatures ◽  
Pattern Of Variation ◽  
Genotypic Control

Longevity in four inbred strains and their hybrids has been studied at two temperatures, 29�5 and 25�C. Heterosis was found at both temperatures but was more extreme at 29� 5�C, which is a very unfavourable environment for D. melanogaster. This observation has its parallel in observations on various fitness factors in several organisms. At 29� 5�C there was more variability of a genotypic nature between the hybrids than at 25�C, perhaps because the adaptation to this unfavourable environment depencls on rather special gene combinations. Thus longevity varies between genotypes, but the pattern of variation depends in an intimate way on the environment.

Studies on Inbred Strains of Drosophila melanogaster

1965 ◽  
Vol 99 (909) ◽  
pp. 495-510 ◽  
Author(s):  
Bruce Wallace ◽  
Carol Madden
Keyword(s):  
Drosophila Melanogaster ◽  
Inbred Strains

scholarly journals Selection on wing allometry in Drosophila melanogaster.

Genetics ◽  
1990 ◽  
Vol 126 (4) ◽  
pp. 975-989 ◽  
Author(s):  
K E Weber
Keyword(s):  
Drosophila Melanogaster ◽  
Additive Genetic Variance ◽  
Bivariate Distribution ◽  
Local Optimum ◽  
Phenotypic Variance ◽  
Isofemale Lines ◽  
Developmental Patterns ◽  
Environmental Regimes ◽  
The Mean ◽  
Lateral Offset

Abstract Five bivariate distributions of wing dimensions of Drosophila melanogaster were measured, in flies 1) subjected to four defined environmental regimes during development, 2) taken directly from nature in seven U.S. states, 3) selected in ten populations for change in wing form, and 4) sampled from 21 long inbred wild-type lines. Environmental stresses during development altered both wing size and the ratios of wing dimensions, but regardless of treatment all wing dimensions fell near a common allometric baseline in each bivariate distribution. The wings of wild-caught flies from seven widely separated localities, and of their laboratory-reared offspring, also fell along the same baselines. However, when flies were selected divergently for lateral offset from these developmental baselines, response to selection was rapid in every case. The mean divergence in offset between oppositely selected lines was 14.68 SD of the base population offset, after only 15 generations of selection at 20%. Measurements of 21 isofemale lines, founded from wild-caught flies and maintained in small populations for at least 22 years, showed large reductions in phenotypic variance of offsets within lines, but a large increase in the variance among lines. The variance of means of isofemale lines within collection localities was ten times the variance of means among localities of newly established wild lines. These observations show that much additive genetic variance exists for individual dimensions within the wing, such that bivariate developmental patterns can be changed in any direction by selection or by drift. The relative invariance of the allometric baselines of wing morphology in nature is most easily explained as the result of continuous natural selection around a local optimum of functional design.

scholarly journals The Effects of Host Age, Host Nuclear Background and Temperature on Phenotypic Effects of the Virulent Wolbachia Strain popcorn in Drosophila melanogaster

Genetics ◽  
2003 ◽  
Vol 164 (3) ◽  
pp. 1027-1034
Author(s):  
K Tracy Reynolds ◽  
Linda J Thomson ◽  
Ary A Hoffmann
Keyword(s):  
Drosophila Melanogaster ◽  
Environmental Temperature ◽  
No Reduction ◽  
Premature Death ◽  
Wolbachia Strain ◽  
Young Males ◽  
Nuclear Background ◽  
Host Mortality ◽  
Two Temperatures ◽  
The Impact

Abstract Because of their obligate endosymbiotic nature, Wolbachia strains by necessity are defined by their phenotypic effects upon their host. Nevertheless, studies on the influence of host background and environmental conditions upon the manifestation of Wolbachia effects are relatively uncommon. Here we examine the behavior of the overreplicating Wolbachia strain popcorn in four different Drosophila melanogaster backgrounds at two temperatures. Unlike other strains of Wolbachia in Drosophila, popcorn has a major fitness impact upon its hosts. The rapid proliferation of popcorn causes cells to rupture, resulting in the premature death of adult hosts. Apart from this effect, we found that popcorn delayed development time, and host background influenced both this trait and the rate of mortality associated with infection. Temperature influenced the impact of popcorn upon host mortality, with no reduction in life span occurring in flies reared at 19°. No effect upon fecundity was found. Contrary to earlier reports, popcorn induced high levels of incompatibility when young males were used in tests, and CI levels declined rapidly with male age. The population dynamics of popcorn-type infections will therefore depend on environmental temperature, host background, and the age structure of the population.

Effet maternel et effet de la vigueur hybride sur la viabilité de la drosophile (Drosophila melanogaster) aux différents stades du développement pré-imaginal

1983 ◽  
Vol 61 (5) ◽  
pp. 1152-1155 ◽  
Author(s):  
Nicole Cadieu
Keyword(s):  
Drosophila Melanogaster ◽  
Maternal Effect ◽  
Death Rate ◽  
Inbred Strains ◽  
The State ◽  
The Other ◽  
Maternal Influence ◽  
Larval Competition ◽  
Larval Life ◽  
Reciprocal Hybrids

When larval competition in Drosophila melanogaster is prevented, survival up to imaginal emergence in two inbred strains and their reciprocal hybrids seems to depend on (i) a maternal influence (possibly due to cytoplasmic factors), (ii) the state of inbreeding or outbreeding of the progeny. The study of the death rate during development demonstrates that the maternal effect can be detected at every stage of the preimaginal life (embryo, larva, and pupa). On the other hand heterosis is superimposed on the maternal effect mainly during larval life, the viability for the hybrid larvae being higher than the average of the two parental strains.

Dominance, allele frequency and selection in a population of Drosophila melanogaster

1980 ◽  
Vol 208 (1171) ◽  
pp. 163-187 ◽  
Keyword(s):  
Drosophila Melanogaster ◽  
Regression Line ◽  
Inbred Lines ◽  
Negative Slope ◽  
Stabilizing Selection ◽  
Recurrent Parent ◽  
Single Pair ◽  
Two Temperatures ◽  
The Mean ◽  
Half Diallel

The numbers of sternopleural chaetae of 18 inbred lines derived from the Texas population of Drosophila melanogaster were ascertained for flies raised at each of two temperatures, 18 and 25°C. Two characters were then defined: M , the average of the chaeta numbers at the two tempera­tures; and S , half of the difference between the average chaeta numbers at the two temperatures. The inbred lines differed among themselves in both characters, so revealing genetic variation in the Texas population for them both. There was no correlation between the values of M and S among the lines. The mean of the inbred lines did not differ significantly from that of the progenies of 22 single-pair matings among flies taken from the population in either character, so suggesting that the 18 inbred lines provided a fair sample of the genes in the population. The differ­ences between the variances among the inbred lines, on the one hand, and the biparental progenies, on the other, suggested that dominance was present for both characters and that dominant alleles were, in general, present at higher frequencies than their recessive fellows. This was confirmed by a half-diallel experiment with 11 of the 18 inbred lines as parents. The half-diallel further showed that dominance was ambidirectional for character S , but gave no conclusive evidence in this respect for M . The theoretical consequences of ambidirectional dominance combined with higher frequencies of dominant alleles were considered for a simple model involving four loci. This showed, in particular, that when one homozygous line (the recurrent parent) is crossed to a number of other lines (the non-recurrent parents), the amount by which the phenotype of the F 1 exceeds the mean of its two parents shows a regres­sion of negative slope on the phenotype of the non-recurrent parent. The regression line is expected to cut the axis of zero excess at a point that is, on average, as far away from the phenotype of maximum dominance as is the expression of the character in the recurrent parent, but in the opposite direction. The point mid-way between the recurrent parent and the inter­cept thus provides an estimate of the phenotype of maximum dominance. Estimates of the phenotypes of maximum dominance were obtained in this way for both characters, M and S , by means of data from the half-diallel and from a further experiment carried out for the purpose. For character M , the phenotype of maximum dominance does not depart significantly from the mean of the inbreds or from that of the Texas population itself; but, for S , though close to the means, it is significantly higher than them. It is concluded that this type of genetical architecture is to be expected with characters under stabilizing selection and that the phenotype of maximum dominance is the optimal phenotype towards which the selection has been acting.

scholarly journals Decanalization of wing development accompanied the evolution of large wings in high-altitude Drosophila

2016 ◽  
Vol 113 (4) ◽  
pp. 1014-1019 ◽  
Author(s):  
Justin B. Lack ◽  
Matthew J. Monette ◽  
Evan J. Johanning ◽  
Quentin D. Sprengelmeyer ◽  
John E. Pool
Keyword(s):  
Drosophila Melanogaster ◽  
Molecular Mechanisms ◽  
Developmental Process ◽  
Morphological Evolution ◽  
Inbred Strains ◽  
Stabilizing Selection ◽  
Wing Development ◽  
Wing Size ◽  
Developmental Networks ◽  
Developmental Buffering

In higher organisms, the phenotypic impacts of potentially harmful or beneficial mutations are often modulated by complex developmental networks. Stabilizing selection may favor the evolution of developmental canalization—that is, robustness despite perturbation—to insulate development against environmental and genetic variability. In contrast, directional selection acts to alter the developmental process, possibly undermining the molecular mechanisms that buffer a trait’s development, but this scenario has not been shown in nature. Here, we examined the developmental consequences of size increase in highland Ethiopian Drosophila melanogaster. Ethiopian inbred strains exhibited much higher frequencies of wing abnormalities than lowland populations, consistent with an elevated susceptibility to the genetic perturbation of inbreeding. We then used mutagenesis to test whether Ethiopian wing development is, indeed, decanalized. Ethiopian strains were far more susceptible to this genetic disruption of development, yielding 26 times more novel wing abnormalities than lowland strains in F2 males. Wing size and developmental perturbability cosegregated in the offspring of between-population crosses, suggesting that genes conferring size differences had undermined developmental buffering mechanisms. Our findings represent the first observation, to our knowledge, of morphological evolution associated with decanalization in the same tissue, underscoring the sensitivity of development to adaptive change.

scholarly journals Polygenic mutation in Drosophila melanogaster: estimates from response to selection of inbred strains.

Genetics ◽  
1994 ◽  
Vol 136 (3) ◽  
pp. 937-951 ◽  
Author(s):  
T F Mackay ◽  
J D Fry ◽  
R F Lyman ◽  
S V Nuzhdin
Keyword(s):  
Drosophila Melanogaster ◽  
Artificial Selection ◽  
Inbred Strains ◽  
Response To Selection ◽  
Environmental Variance ◽  
Rapid Responses ◽  
Bristle Number ◽  
Mutational Variance ◽  
Selection Of ◽  
New Mutations

Abstract Replicated divergent artificial selection for abdominal and sternopleural bristle number from a highly inbred strain of Drosophila melanogaster resulted in an average divergence after 125 generations of selection of 12.0 abdominal and 8.2 sternopleural bristles from the accumulation of new mutations affecting bristle number. Responses to selection were highly asymmetrical, with greater responses for low abdominal and high sternopleural bristle numbers. Estimates of VM, the mutational variance arising per generation, based on the infinitesimal model and averaged over the responses to the first 25 generations of selection, were 4.32 x 10(-3) VE for abdominal bristle number and 3.66 x 10(-3) VE for sternopleural bristle number, where VE is the environmental variance. Based on 10 generations of divergent selection within lines from generation 93, VM for abdominal bristle number was 6.75 x 10(-3) VE and for sternopleural bristle number was 5.31 x 10(-3) VE. However, estimates of VM using the entire 125 generations of response to selection were lower and generally did not fit the infinitesimal model largely because the observed decelerating responses were not compatible with the predicted increasing genetic variance over time. These decelerating responses, periods of response in the opposite direction to artificial selection, and rapid responses to reverse selection all suggest new mutations affecting bristle number on average have deleterious effects on fitness. Commonly observed periods of accelerated responses followed by long periods of stasis suggest a leptokurtic distribution of mutational effects for bristles.

scholarly journals Elevation of linkage disequilibrium above neutral expectations in ancestral and derived populations of Drosophila melanogaster

2015 ◽  
Author(s):  
Nandita R. Garud ◽  
Dmitri A. Petrov
Keyword(s):  
Drosophila Melanogaster ◽  
Long Range ◽  
Natural Populations ◽  
Inbred Strains ◽  
Population Substructure ◽  
Ancestral Population ◽  
Rate Variation ◽  
Data Set ◽  
Adaptive Mutations ◽  
Haploid Embryos

The extent to which selection and demography impact patterns of genetic diversity in natural populations of Drosophila melanogaster is yet to be fully understood. We previously observed that the pattern of LD at scales of ~10 kb in the Drosophila Genetic Reference Panel (DGRP), consisting of 145 inbred strains from Raleigh, North Carolina, measured both between pairs of sites and as haplotype homozygosity, is elevated above neutral demographic expectations. Further, we demonstrated that signatures of strong and recent soft sweeps are abundant. However, the extent to which this pattern is specific to this derived and admixed population is unknown. Neither is it clear whether such a pattern may have arisen as a consequence of the extensive inbreeding performed to generate the DGRP data. Here we analyze > 100 fully sequenced strains from Zambia, an ancestral population to the Raleigh population, that has experienced little to no admixture and was generated by sequencing haploid embryos rather than inbred strains. This data set allows us to determine whether patterns of elevated LD and signatures of abundant soft sweeps are generic to multiple populations of D. melanogaster or whether they are generated either by inbreeding, bottlenecks or admixture in the DGRP dataset. We find an elevation in long-range LD and haplotype homozygosity in the Zambian dataset, confirming the result from the DGRP data set. This elevation in LD and haplotype structure remains even after controlling for many sources of LD in the data including genomic inversions, admixture, population substructure, close relatedness of individual strains, and recombination rate variation. Furthermore, signatures of partial soft sweeps similar to those found in the DGRP are common in Zambia. These results suggest that while the selective forces and sources of adaptive mutations may differ in Zambia and Raleigh, elevated long-range LD and signatures of soft sweeps are generic in D. melanogaster.

scholarly journals The occurrence of long ribosomal transcripts homologous to type I insertions in bobbed mutants of Drosophila melanogaster

1989 ◽  
Vol 54 (2) ◽  
pp. 127-135 ◽  
Author(s):  
Mohamed Makni ◽  
Mohamed Marrakchi ◽  
Nicole Prud'Homme
Keyword(s):  
Drosophila Melanogaster ◽  
Ribosomal Genes ◽  
Type I ◽  
Wild Type ◽  
Coding Region ◽  
Rdna Genes ◽  
Sandwich Hybridization ◽  
Number Of Genes ◽  
In The Wild ◽  
Two Temperatures

SummaryIn Drosophila melanogaster up to two thirds of the rDNA genes contain insertion sequences of two types in the 28S coding region. Comparison of the ribosomal insertion transcripts in the wild type and in two bobbed mutants reared at two temperatures showed that the level of type I transcripts is dependent on both the number of genes with type I insertions in the bobbed loci and the intensity of bobbed phenotype. Importantly, a long transcript of 8·7 kb hybridized to the ribosomal probe, the INS I probe and also to the restriction fragment of the rDNA downstream of the point of insertion was found in one bobbed mutant. This result and also those from sandwich hybridization indicate that some interrupted ribosomal genes are functional.

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