scholarly journals A quantitative genetic analysis of fitness and its components in Drosophila melanogaster

1986 ◽  
Vol 47 (1) ◽  
pp. 59-70 ◽  
Author(s):  
Trudy F. C. Mackay
Keyword(s):  
Drosophila Melanogaster ◽  
Natural Populations ◽  
Strongly Correlated ◽  
Wild Type ◽  
Relative Contribution ◽  
Quantitative Characters ◽  
Quantitative Genetic ◽  
Bristle Number ◽  
Metric Traits ◽  
Average Fitness

SummaryForty-one third chromosomes extracted from a natural population of Drosophila melanogaster were assessed for net fitness and for the quantitative characters viability, net fertility, female productivity, male weight, abdominal bristle number, and sternopleural bristle number. Net homozygous and heterozygous fitness of the third chromosomes was estimated by competition against a marked balancer third chromosome. Average fitness of the homozygous lines relative to wild-type heterozygotes was 0·13, indicating substantial inbreeding depression for net fitness. All significant correlations of quantitative characters with fitness and with each other were high and positive. Homozygous fitness is strongly correlated with net fertility, viability, and female productivity, moderately associated with male weight, and not significantly associated with bristle traits. The combination of metric traits which best predicts homozygous fitness is the simple multiple of viability and female productivity. Heterozygous fitness is not correlated with homozygous fitness; furthermore, the relative contribution of metric traits to fitness in a heterozygous population is likely to be different from that deduced from homozygous lines. These observations are consistent with a model of genetic variation for fitness in natural populations caused by segregation of rare deleterious recessive alleles.

scholarly journals Genetic variation affecting heart rate in Drosophila melanogaster

1999 ◽  
Vol 74 (2) ◽  
pp. 121-128 ◽  
Author(s):  
J. ROBBINS ◽  
R. AGGARWAL ◽  
R. NICHOLS ◽  
G. GIBSON
Keyword(s):  
Heart Rate ◽  
Drosophila Melanogaster ◽  
Heart Function ◽  
Susceptibility Gene ◽  
Natural Populations ◽  
Model Organism ◽  
Genetic Dissection ◽  
Wild Type ◽  
Quantitative Genetic ◽  
Wide Range

Heart rate in pre-pupae of Drosophila melanogaster is shown to vary over a wide range from 2·5 to 3·7 beats per second. Quantitative genetic analysis of a sample of 11 highly inbred lines indicates that approaching one-quarter of the total variance in natural populations can be attributed to genetic differences between flies. A hypomorphic allele of the potassium channel gene ether-a-gogo, which is homologous to a human long-QT syndrome susceptibility gene (HERG), has a heart rate at the low end of the wild-type range, but this effect can be suppressed in certain wild-type genetic backgrounds. This study provides a baseline for investigation of pharmacological and other physiological influences on heart rate in the model organism, and implies that quantitative genetic dissection will provide insight into the molecular basis for variation in normal and arrhythmic heart function.

scholarly journals Hybrid dysgenesis-induced quantitative variation on the X chromosome of Drosophila melanogaster.

Genetics ◽  
1990 ◽  
Vol 124 (3) ◽  
pp. 627-636
Author(s):  
C Q Lai ◽  
T F Mackay
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Quantitative Traits ◽  
Natural Populations ◽  
Quantitative Variation ◽  
Hybrid Dysgenesis ◽  
X Chromosomes ◽  
Bristle Number ◽  
Seven Generations ◽  
Polygenic Variation

Abstract To determine the ability of the P-M hybrid dysgenesis system of Drosophila melanogaster to generate mutations affecting quantitative traits, X chromosome lines were constructed in which replicates of isogenic M and P strain X chromosomes were exposed to a dysgenic cross, a nondysgenic cross, or a control cross, and recovered in common autosomal backgrounds. Mutational heritabilities of abdominal and sternopleural bristle score were in general exceptionally high-of the same magnitude as heritabilities of these traits in natural populations. P strain chromosomes were eight times more mutable than M strain chromosomes, and dysgenic crosses three times more effective than nondysgenic crosses in inducing polygenic variation. However, mutational heritabilities of the bristle traits were appreciable for P strain chromosomes passed through one nondysgenic cross, and for M strain chromosomes backcrossed for seven generations to inbred P strain females, a result consistent with previous observations on mutations affecting quantitative traits arising from nondysgenic crosses. The new variation resulting from one generation of mutagenesis was caused by a few lines with large effects on bristle score, and all mutations reduced bristle number.

scholarly journals A quantitative genetic study of starvation resistance at different geographic scales in natural populations of Drosophila melanogaster

2010 ◽  
Vol 92 (4) ◽  
pp. 253-259 ◽  
Author(s):  
JULIETA GOENAGA ◽  
JUAN JOSÉ FANARA ◽  
ESTEBAN HASSON
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Correlations ◽  
Natural Populations ◽  
Food Shortage ◽  
Population Variation ◽  
Phenotypic Variance ◽  
Starvation Resistance ◽  
Natural Genetic Variation ◽  
Quantitative Genetic ◽  
Variation Explained

SummaryFood shortage is a stress factor that commonly affects organisms in nature. Resistance to food shortage or starvation resistance (SR) is a complex quantitative trait with direct implications on fitness. However, surveys of natural genetic variation in SR at different geographic scales are scarce. Here, we have measured variation in SR in sets of lines derived from nine natural populations of Drosophila melanogaster collected in western Argentina. Our study shows that within population variation explained a larger proportion of overall phenotypic variance (80%) than among populations (7·2%). We also noticed that an important fraction of variation was sex-specific. Overall females were more resistant to starvation than males; however, the magnitude of the sexual dimorphism (SD) in SR varied among lines and explained a significant fraction of phenotypic variance in all populations. Estimates of cross-sex genetic correlations suggest that the genetic architecture of SR is only partially shared between sexes in the populations examined, thus, facilitating further evolution of the SD.

scholarly journals Quantitative genetic variation of enzyme activities in natural populations of Drosophila melanogaster

1980 ◽  
Vol 77 (2) ◽  
pp. 1073-1077 ◽  
Author(s):  
C. C. Laurie-Ahlberg ◽  
G. Maroni ◽  
G. C. Bewley ◽  
J. C. Lucchesi ◽  
B. S. Weir
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Enzyme Activities ◽  
Natural Populations ◽  
Quantitative Genetic

scholarly journals Studies on The Scutellar Bristles of Drosophila Melanogaster I. Basic Variability, Some Temperature and Culture Effects, and Responses to Short-Term Selection in the Oregon-Rc Strain

1968 ◽  
Vol 21 (4) ◽  
pp. 721 ◽  
Author(s):  
BL Sheldon
Keyword(s):  
Drosophila Melanogaster ◽  
Major Gene ◽  
Selection Response ◽  
Wild Type ◽  
Short Term ◽  
Term Selection ◽  
Bristle Number ◽  
Selection For ◽  
High Selection ◽  
Culture Effects

The results of short runs of disruptive and high selection for scutellar bristles in wild-type Drosophila are explained in terms of the hypothesis that canalization at four bristles is due to regulation of the major gene in the developmental system (Rendel, Sheldon, and Finlay 1965). Selection response has probably been due to selection for modifier (minor) genes rather than for isoalleles of the major gene or weak regulator alleles. Some environmental effects on the character, short runs of selection for low bristle number or different bristle types, and effects of relaxing selection are also reported.

The action of evolutionary forces on metric traits

2011 ◽  
Vol 1 (3) ◽  
pp. 532-537
Author(s):  
C. López-Fanjul
Keyword(s):  
Genetic Variance ◽  
Natural Populations ◽  
Substantial Contribution ◽  
Additive Variance ◽  
Evolutionary Forces ◽  
Bristle Number ◽  
Laboratory Populations ◽  
Component Traits ◽  
Mean Fitness ◽  
Metric Traits

Fisher's theorem of natural selection implies that the population genetic variance of quasi-neutral traits should be mostly additive. In the case of fitness component traits, however, that variance would be characterised by a substantial contribution from non-additive loci. In parallel, Robertson's theorem states that selection will change the population mean of a trait proportionally to the magnitude of the genetic correlation between that trait and fitness, which should be weak for quasi-neutral traits or strong for the mean fitness components. Drosophila data from inbreeding and artificial selection experiments are discussed within that theoretical framework. In addition, the process of regeneration by mutation of the genetic variance of a quasi-neutral trait (abdominal bristle number) in a Drosophila population initially homozygous at all loci has been analysed. After 485 generations of mutation accumulation, the levels of additive variance found in this population closely approached those commonly observed in laboratory populations. Furthermore, these values, together with previously reported estimates for natural populations, could be jointly explained by a model assuming weak causal stabilising selection.

scholarly journals Selection for and against a canalized phenotype in Drosophila melanogaster

1967 ◽  
Vol 10 (1) ◽  
pp. 21-33 ◽  
Author(s):  
S. S. Y. Young
Keyword(s):  
Drosophila Melanogaster ◽  
Lower Proportion ◽  
Modifier Genes ◽  
Wild Type ◽  
Appreciable Change ◽  
Bristle Number ◽  
Alternative Hypotheses ◽  
Males And Females ◽  
Selection For ◽  
Relative Change

Selection for and against the canalized phenotype in scutellar bristles was attempted in two selection lines and a randomly selected line was used as control. The selection lines were the Decanalization line (D) and the Canalization line (N). The D line was maintained by matings of scute males (scwbl) with three scutellars with wild-type females (scwbl/yw) with five bristles, in the N line scute males with four bristles were mated with wild-type females also with four bristles, while in the C line males and females of the above genotypes were selected at random. The lines were established from a sample of flies taken from a line selected for high scutellar numbers.After eighteen generations of selection the C line was characterized by a regression of mean bristle number without appreciable change in variance. Relative to the N line, the D population showed a lower proportion of flies having four scutellars, a higher variance in bristle numbers, and a higher proportion of four-bristle scute flies having abnormal patterns.Two alternative hypotheses were advanced to account for the results of this experiment. The first postulated a relative change in the widths of the four-bristle canalization zones in the selection lines, while the second suggested a relative change in frequencies of specific modifier genes for scutellars in scute and in wild-type genotypes of the lines. The evidence favours the latter hypothesis.

scholarly journals Phenotypic and genomic analysis of P elements in natural populations of Drosophila melanogaster

2016 ◽  
Author(s):  
I.A. Kozeretska ◽  
V. Bondarenko ◽  
V.I. Shulga ◽  
S.V. Serga ◽  
A.I. Rozhok ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Active Form ◽  
Natural Populations ◽  
Genomic Analysis ◽  
Element Composition ◽  
Strongly Correlated ◽  
Mobile Dna ◽  
P Elements ◽  
The Stability ◽  
Genomic Basis

AbstractThe Drosophila melanogaster P transposable element provides one of the best cases of horizontal transfer of a mobile DNA sequence in eukaryotes. Invasion of natural populations by the P element has led to a syndrome of phenotypes known as “P-M hybrid dysgenesis” that emerges when strains differing in their P element composition mate and produce offspring. Despite extensive research on many aspects of P element biology, questions remain about the stability and genomic basis of variation in P-M dysgenesis phenotypes. Here we report the P-M status for a number of populations sampled recently from Ukraine that appear to be undergoing a shift in their P element composition. Gondal dysgenesis assays reveal that Ukrainian populations of D. melanogaster are currently dominated by the P’ cytotype, a cytotype that was previously thought to be rare in nature, suggesting that a new active form of the P element has recently spread in this region. We also compared gondal dysgenesis phenotypes and genomic P element predictions for isofemale strains obtained from three worldwide populations of D. melanogaster in order to guide further work on the molecular basis of differences in cytotype status across populations. We find that the number of euchromatic P elements per strain can vary significantly across populations but that total P element numbers are not strongly correlated with the degree of gondal dysgenesis. Our work shows that rapid changes in cytotype status can occur in natural populations of D. melanogaster, and informs future efforts to decode the genomic basis of geographic and temporal differences in P element induced phenotypes.

scholarly journals ESTIMATION OF FITNESS COMPONENTS IN DROSOPHILA MELANOGASTER. I. HETEROZYGOTE VIABILITY INDICES

Genetics ◽  
1978 ◽  
Vol 88 (1) ◽  
pp. 139-148
Author(s):  
Alan J Katz ◽  
Ricardo A Cardellino
Keyword(s):  
Drosophila Melanogaster ◽  
Natural Populations ◽  
Reciprocal Effects ◽  
Wild Type ◽  
Genotypic Variance ◽  
Fitness Components ◽  
Marker Chromosomes ◽  
The Future ◽  
Relative Viability

ABSTRACT We examine the assumption of "dominance" with regard to viability of the Cy and Pm marker chromosomes in D. melanogaster. This assumption is often invoked for the extraction of wild-type second chromosomes from natural populations and for the calculation of relative viability indices. Significant genotypic variances for viability are found among both C y / f i and P m / f i heterozygotes in California and Japanese populations. The magnitude of the Pm/+i genotypic variance is substantially less than that of the Cy/+j heterozygotes (less than one half). Significant reciprocal effects are also found to influence Cy/+j, Pm/+i and + J f j viabilities. We conclude that viability indices of heterozygotes based on the Curly method are biased. We suggest that viability indices in the future be expressed relative to the viability of the Cy/Pm genotype (Curly-Plum method) or possibly that of the Pm/+i genotype (Plum method).

scholarly journals The evolutionary potential of diet-dependent effects on lifespan and fecundity in a multi-parental population of Drosophila melanogaster

2018 ◽  
Author(s):  
Enoch Ng’oma ◽  
Wilton Fidelis ◽  
Kevin M. Middleton ◽  
Elizabeth G. King
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Genetic Correlations ◽  
Natural Populations ◽  
Evolutionary Potential ◽  
Fitness Components ◽  
Nutrient Imbalance ◽  
Quantitative Genetic ◽  
Nutritional Conditions ◽  
Quantitative Genetic Parameters

AbstractThe nutritional conditions experienced by a population play a major role in shaping trait evolution in many taxa. Constraints exerted by nutrient limitation or nutrient imbalance can influence the maximal value that fitness components such as reproduction and lifespan attains, and organisms may shift how resources are allocated to different structures and functions in response to changes in nutrition. Whether the phenotypic changes associated with changes in nutrition represent an adaptive response is largely unknown. Further, it is unclear whether the response of fitness components to diet even has the potential to evolve in most systems. In this study, we use an admixed multiparental population of Drosophila melanogaster reared in three different diet conditions to estimate quantitative genetic parameters for lifespan and fecundity. We find significant genetic variation for both traits in our population and show that lifespan has moderate to high heritabilities within diets. Genetic correlations for lifespan between diets were significantly less than one, demonstrating a strong genotype by diet interaction. These findings demonstrate substantial standing genetic variation in our population that is comparable to natural populations and highlights the potential for adaptation to changing nutritional environments.

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