scholarly journals Quantitative inheritance of red eye pigment in Drosophila melanogaster

1966 ◽  
Vol 8 (2) ◽  
pp. 143-164 ◽  
Author(s):  
Narendra S. Chauhan ◽  
Forbes W. Robertson
Keyword(s):  
Drosophila Melanogaster ◽  
Body Size ◽  
Wild Population ◽  
Inbred Lines ◽  
Pigment Content ◽  
Phenotypic Variance ◽  
Family Selection ◽  
Genetic Determination ◽  
Red Eye ◽  
Selection For

1. The genetic and environmental variation of red eye pigment in individuals of a wild population of Drosophila melanogaster has been studied by extracting and measuring the pigment content of individual flies, which were also scored for eye and body size.2. Comparison of such variability in the wild population with the individual variation in crosses between inbred lines suggested that 60% of the phenotypic variance is genetic. About 75% of both genetic and environmental variance is due to intrinsic variation of pigment content while the remainder is correlated with eye size, which shows appreciable variation, independent of general body size, as measured by thorax length.3. Selection for high and low pigment content by both phenotypic and family selection led to 40–50% differences between high and low lines after eight genera tions. The response was asymmetrical and proceeded further and faster with selection for lower pigment content. Crosses between high and low lines showed positive departure from intermediacy, suggesting that more or less recessive effects had contributed to the selection for lower pigment content.4. There was some evidence of lower viability in the selected lines but no evidence of lower fertility or gamete viability in more extreme individuals of either sex.5. Comparison of pigment content, eye and body size at different temperatures and under different levels of crowding suggested that the pigment content per ommatidium is subject to a high degree of genetic determination.6. The average pigment content in strains derived from widely separated localities showed substantial variation, independent of both eye and body size.7. Inbred lines, derived from the same population, were found to differ greatly in pigment content. Crosses and the exchange of homologous pairs of chromosomes between two of these lines suggested that one or more completely recessive genes were fixed in both the second and third chromosome of one line, while the same second chromosome effect was also fixed in another line. The second and third chromosome difference reduced pigment content by respectively 30% and 50% and combined additively, judging by the effects of single and joint substitutions of homologous pairs.8. The possibility of combining genetic and biochemical analysis of pigment content is discussed.

scholarly journals The quantitative relations between variation in red eye pigment and related pteridine compounds inDrosophila melanogaster

1970 ◽  
Vol 15 (1) ◽  
pp. 65-86 ◽  
Author(s):  
Ilse B. Barthelmess ◽  
Forbes W. Robertson
Keyword(s):  
Genetic Variation ◽  
Biochemical Properties ◽  
Pigment Content ◽  
Red Pigment ◽  
Base Population ◽  
Stock Selection ◽  
Metabolic Pattern ◽  
Red Eye ◽  
Genetic Behaviour ◽  
Selection For

SUMMARYThe relations between the quantity of red eye pigment and related pteridine compounds ofDrosophila melanogasterhave been studied in a variety of genotypes, which include strains selected for high or low pigment content, various derivatives of these lines and also lines in which one or other of the major autosome pairs were represented by homozygous chromosome pairs, derived by random sampling from the base population and also inbred lines. The quantity of red pigment was defined by the optical density when whole heads were extracted in a suitable solvent, while the pteridines were separated by chromatography and their amounts estimated by means of their characteristic fluorescence.The evidence from selection, inbreeding and chromosome sampling from the base population demonstrated the presence of substantial genetic variation for pigment content and amounts of related pteridines.The genetic and biochemical properties of the selected lines differed according to the direction of selection. High lines remained heterozygous after many generations of selection and displayed dominance and epistasis in favour of higher pigment content in crosses to the unselected stock. Selection for low pigment content led to fixation of recessive effects, attributable to particular chromosomes. The dominance-recessive relationship in red pigment differences was also applicable to the associated pteridines.The metabolic pattern in all lines with reduced pigment content is compatible with the assumption of reduced enzyme activity at particular steps of the pathway leading to the drosopterins (red eye pigments). The two steps accessible to study are subject to genetic variation in the base population, while inbreeding or selection for low pigment content leads to genetically fixed alterations at one or other of these steps. The genetic analysis was consistent with the biochemical evidence.Increase in pigment content above the normal level, either by selection or chance fixation, is accompanied by correlated increase in all the precursors. Several alternatives are possible but it is suggested that this may be due to an increase in early precursors, before the stages which have been altered in the low pigment lines.Attention is drawn to the similarity in genetic behaviour between pigment content and body size. Particular emphasis is laid on the value of selection as a means of creating biochemical differences which offer a basis for relating biochemical function and genetic behaviour.

scholarly journals Correlated responses to selection on body size in Drosophila melanogaster

1999 ◽  
Vol 74 (1) ◽  
pp. 43-54 ◽  
Author(s):  
LINDA PARTRIDGE ◽  
ROSALIE LANGELAN ◽  
KEVIN FOWLER ◽  
BAS ZWAAN ◽  
VERNON FRENCH
Keyword(s):  
Growth Rate ◽  
Drosophila Melanogaster ◽  
Body Size ◽  
Larval Development ◽  
Growth Period ◽  
Cell Number ◽  
Correlated Responses ◽  
Larval Weight ◽  
Thorax Length ◽  
Selection For

Correlated responses to artificial selection on body size in Drosophila melanogaster were investigated, to determine how the changes in size were produced during development. Selection for increased thorax length was associated with an increase in larval development time, an extended growth period, no change in growth rate, and an increased critical larval weight for pupariation. Selection for reduced thorax length was associated with reduced growth rate, no change in duration of larval development and a reduced critical larval weight for pupariation. In both lines selected for thorax length and lines selected for wing area, total body size changed in the same direction as the artificially selected trait. In large selection lines of both types, the increase in size was achieved almost entirely by an increase in cell number, while in the small lines the decrease in size was achieved predominantly by reduced cell size, and also by a reduction in cell number. The implications of the results for evolutionary-genetic change in body size in nature are discussed.

The Changes in Genetic and Environmental Variance With Inbreeding in Drosophila melanogaster

Genetics ◽  
1999 ◽  
Vol 152 (1) ◽  
pp. 345-353 ◽  
Author(s):  
Michael C Whitlock ◽  
Kevin Fowler
Keyword(s):  
Drosophila Melanogaster ◽  
Large Scale ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Inbred Lines ◽  
Residual Variance ◽  
Phenotypic Variance ◽  
Population Bottlenecks ◽  
Environmental Variance ◽  
Components Of Variance

Abstract We performed a large-scale experiment on the effects of inbreeding and population bottlenecks on the additive genetic and environmental variance for morphological traits in Drosophila melanogaster. Fifty-two inbred lines were created from the progeny of single pairs, and 90 parent-offspring families on average were measured in each of these lines for six wing size and shape traits, as well as 1945 families from the outbred population from which the lines were derived. The amount of additive genetic variance has been observed to increase after such population bottlenecks in other studies; in contrast here the mean change in additive genetic variance was in very good agreement with classical additive theory, decreasing proportionally to the inbreeding coefficient of the lines. The residual, probably environmental, variance increased on average after inbreeding. Both components of variance were highly variable among inbred lines, with increases and decreases recorded for both. The variance among lines in the residual variance provides some evidence for a genetic basis of developmental stability. Changes in the phenotypic variance of these traits are largely due to changes in the genetic variance.

scholarly journals Adaptation to environmental heterogeneity in populations of Drosophila melanogaster

1987 ◽  
Vol 49 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Margriet V. Verdonck
Keyword(s):  
Drosophila Melanogaster ◽  
Environmental Heterogeneity ◽  
Additive Genetic Variance ◽  
Coarse Grained ◽  
Salt Medium ◽  
Family Selection ◽  
Salt Treatment ◽  
Fitness Set ◽  
Selection For ◽  
Optimal Medium

SummaryFor 29 generations, populations of Drosophila melanogaster were offered one favourable (standard) and one suboptimal (salt-supplemented) medium, either singly or simultaneously. Egg-to-adult viability, fecundity and choice of oviposition medium were measured at regular intervals on both resources up to 17 generations after initiation of the salt treatment. Except for a decrease in viability on salt medium in the single-resource populations (SRPs) maintained on the optimal medium, these fitness components remained unchanged. Estimation of a more inclusive measure of fitness, productivity, obtained at generations 27–29, revealed that: (1) the SRPs maintained on salt medium were more adapted to salt medium; (2) the mixed-resource populations (MRPs) were intermediate in their adaptation to salt medium between either type of single-resource population. These results support Levins' model of optimal strategy for populations living in a coarse-grained environment when the fitness set is convex. Family selection for increased and decreased resistance to salt in the medium, carried out for the viability component at generations nine and 19, showed that: (1) genetic variation with respect to this component was present in all populations; (2) the SRPs maintained on salt medium had responded to the salt treatment by eliminating sensitive genotypes; (3) in the first selection experiment, the MRPs had a greater amount of additive genetic variance with respect to viability than either type of SRP; in the second experiment, this difference was not significant, but it was in the predicted direction. The latter finding provides some evidence in favour of the hypothesis repeatedly presented in the literature that environmental heterogeneity could promote the maintenance of genetic variability in populations.

Genetics of coxal chaetae in Drosophila melanogaster II. Responses to selection

1978 ◽  
Vol 202 (1147) ◽  
pp. 211-230 ◽  
Keyword(s):  
Drosophila Melanogaster ◽  
Inbred Lines ◽  
Correlated Responses ◽  
X Chromosomes ◽  
True Breeding ◽  
Selection Experiments ◽  
Complicating Factors ◽  
Polygenic System ◽  
Selection For

The average number of chaetae borne by the coxae is lowest on the rear (R) legs, intermediate on the middle (M) legs and highest on the front (F) legs. Mather & Hanks (1978) have shown that the numbers of coxal chaetae are mediated by a polygenic system. On the basis of evidence from a survey of inbred lines, chromosome assays of the differences among three of these lines, and a survey of the distribution of genic differences along the X chromosomes of the same three lines they postulated three kinds of gene in this system : α genes active on all three legs; β genes inactive on the rear legs, but active on the middle and front legs; and γ genes active only on the front legs. From this hypothesis, expectations are now derived for the responses of chaeta number on all three kinds of leg to selection for increased (H) and decreased (L) numbers of chaetae on the rear legs ( R H and R L ), on the middle legs ( M H and M L ) and on the front legs ( F H and F L ); and for increased and decreased differences between the chaeta numbers of the front and middle legs (( F – M ) H and ( F – M ) L ), of the front and rear legs (( F – R ) H and ( F – R ) L ), and of the middle and rear legs (( M – R ) H and ( M – R ) L ). The basic expectations are subject to prospective disturbance by certain complicating factors, notably by differences among the legs in heritability of the variation in chaeta number and by correlated responses to the selection arising from linkage between genes of the different kinds. Starting with the F 2 of a cross between two true-breeding stocks, twelve selection lines were initiated, one for each of the twelve types of selection, and continued for a minimum of 10 generations. It is shown that the responses in the chaetae numbers of the three kinds of leg to the twelve types of selection accord with expectation. Indeed, the results of the selection experiments of themselves lead directly to the hypothesis of the three kinds of gene.

scholarly journals A QTL analysis of female variation contributing to refractoriness and sperm competition in Drosophila melanogaster

2005 ◽  
Vol 86 (2) ◽  
pp. 107-114 ◽  
Author(s):  
MARA K. N. LAWNICZAK ◽  
DAVID J. BEGUN
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Sperm Competition ◽  
Competitive Ability ◽  
Recombinant Inbred Lines ◽  
Inbred Lines ◽  
Phenotypic Variance ◽  
Fitness Component ◽  
Male Sperm ◽  
Trait Locus

Sperm competition is an important fitness component in many animal groups. Drosophila melanogaster males exhibit substantial genetic variation for sperm competitive ability and females show considerable genetic variation for first versus second male sperm use. Currently, the forces responsible for maintaining genetic variation in sperm competition related phenotypes are receiving much attention. While several candidate genes contributing to the variation seen in male competitive ability are known, genes involved in female sperm use remain largely undiscovered. Without knowledge of the underlying genes, it will be difficult to distinguish between different models of sexual selection such as cryptic female choice and sexual conflict. We used quantitative trait locus (QTL) mapping to identify regions of the genome contributing to female propensity to use first or second male sperm, female refractoriness to re-mating, and early-life fertility. The most well supported markers influencing the phenotypes include 33F/34A (P2), 57B (refractoriness) and 23F/24A (fertility). Between 10% and 15% of the phenotypic variance observed in these recombinant inbred lines was explained by these individual QTLs. More detailed investigation of the regions detected in this experiment may lead to the identification of genes responsible for the QTLs identified here.

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