scholarly journals The effect of suppressing crossing-over on the response to selection in Drosophila melanogaster

1970 ◽  
Vol 16 (1) ◽  
pp. 1-16 ◽  
Author(s):  
C. P. McPhee ◽  
Alan Robertson
Keyword(s):  
Drosophila Melanogaster ◽  
Dominant Gene ◽  
Crossing Over ◽  
Linkage Equilibrium ◽  
Selection Experiment ◽  
Base Population ◽  
Response To Selection ◽  
Wild Type ◽  
Segregation Ratios

SUMMARYA selection experiment for sternopleural bristles in Drosophila melanogaster was undertaken to measure the effect of suppressing crossing-over on chromosomes II and III using the inversions Curly and Moiré marked with a dominant gene, which severely reduce crossing-over. In one set of lines selected wild-type males were mated to selected females, heterozygous for Cy and Mé, and in a parallel set selected males carrying the inversions were mated to selected wild-type females. Because there is no crossing-over in the males in this species, crossing-over is much reduced in the first set and is at its usual level in the second. The effect of the selection was measured on flies which did not carry the inversions. The suppression of crossing-over reduced the advance at the limit by 28 ± 8% for selection upwards and by 22 ± 7% for selection downwards. The segregation ratios of the inversions were observed throughout the experiment. At the end, the proportion of wild-type flies emerging was not different in the two sets of lines. The results are consistent with an assumption of initial linkage equilibrium between loci affecting sternopleural bristles in the base population.

scholarly journals DEVELOPMENT IN GENETIC MOSAICS OF ARISTAPEDIA, A HOMOEOTIC MUTANT OF DROSOPHILA MELANOGASTER

Genetics ◽  
1974 ◽  
Vol 76 (4) ◽  
pp. 767-774
Author(s):  
J H Postlethwait ◽  
J R Girton
Keyword(s):  
Drosophila Melanogaster ◽  
Cell Line ◽  
Crossing Over ◽  
Wild Type ◽  
Genetic Mosaics ◽  
X Ray ◽  
A Cell

ABSTRACT Development of the homoeotic mutation, aristapedia (ss  a), was investigated by means of genetic mosaics. The wild-type alleles of aristapedia and the bristle markers yellow, singed, and forked were removed from cells at different times in development by X-ray induced somatic crossing-over. The phenotype of the resulting clones was examined in order to ascertain whether it was leg or antenna. The y sn f; ssa clones showed a leg phenotype if induced before the mid-third instar, but showed an antennal phenotype if induced after this time. Late non-expression of ss  a may be due either to an influence of surrounding ss  + tissues on the small ss  a clones, or to a persistence of the effect of ss  + for one or two cell generations after it is removed from a cell line.

scholarly journals Response to Selection in Synthetic Lines of Drosophila Melanogaster

1973 ◽  
Vol 26 (3) ◽  
pp. 613 ◽  
Author(s):  
RR Howe ◽  
JW James
Keyword(s):  
Drosophila Melanogaster ◽  
Base Population ◽  
Response To Selection ◽  
Bristle Number ◽  
Experimental Analyses

Response to selection in synthetic lines has been examined by both theoretical and experimental analyses. Synthetic lines were founded from 20 base lines of D. melanogaster all derived from the same base population and which had been selected for high sternopleural bristle number.

scholarly journals Heritability of Directional Asymmetry in Drosophila melanogaster

2009 ◽  
Vol 2009 ◽  
pp. 1-7 ◽  
Author(s):  
Ashley J. R. Carter ◽  
Elizabeth Osborne ◽  
David Houle
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Artificial Selection ◽  
Natural Variation ◽  
The Other ◽  
Directional Asymmetry ◽  
Consistent Difference ◽  
Selection Experiment ◽  
Response To Selection ◽  
Powerful Technique

Directional asymmetry (DA), the consistent difference between a pair of morphological structures in which the same side is always larger than the other, presents an evolutionary mystery. Although many paired traits show DA, genetic variation for DA has not been unambiguously demonstrated. Artificial selection is a powerful technique for uncovering selectable genetic variation; we review and critique the limited number of previous studies that have been performed to select on DA and present the results of a novel artificial selection experiment on the DA of posterior crossvein location in Drosophila wings. Fifteen generations of selection in two genetically distinct lines were performed and none of the lines showed a significant response to selection. Our results therefore support and reconfirm previous findings; despite apparent natural variation and evolution of DA in nature, DA remains a paradoxical trait that does not respond to artificial selection.

scholarly journals Unequal crossing-over within the B duplication of Drosophila melanogaster: a molecular analysis

1991 ◽  
Vol 57 (2) ◽  
pp. 105-111 ◽  
Author(s):  
Stuart I. Tsubota
Keyword(s):  
Drosophila Melanogaster ◽  
Transposable Element ◽  
Molecular Analysis ◽  
Recombination Event ◽  
Tandem Duplication ◽  
Molecular Data ◽  
Crossing Over ◽  
Wild Type ◽  
Unequal Crossing Over ◽  
Extreme Form

SummaryThe B mutation is associated with a tandem duplication of 16A1–16A7. It is unstable, mutating to wild type and to a more extreme form at a frequency of one in 1000 to 3000. The reversion to wild type is associated with the loss of one copy of the duplication, whereas the mutation to extreme B is associated with a triplication of the region. The instability of B has been attributed to unequal crossing-over between the two copies of the duplication. Recent molecular data show that there is a transposable element, B104, between the two copies of the duplication and support the hypothesis that this element generated the duplication via a recombination event. These data suggest that unequal crossing-over within the duplication may not be the cause of the instability of B. Instead, the instability may be caused by a recombination event involving the B104 element. This issue was addressed using probes for the DNA on either side of the B104 element at the B breakpoint. All of the data indicate that the B104 element is not involved in the instability of B and support the original unequal crossing-over model.

scholarly journals THE ORGANIZATION OF GENETIC VARIATION FOR RECOMBINATION IN DROSOPHILA MELANOGASTER

Genetics ◽  
1986 ◽  
Vol 114 (2) ◽  
pp. 525-547
Author(s):  
Lisa D Brooks ◽  
R William Marks
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Natural Population ◽  
Small Region ◽  
Crossing Over ◽  
Fine Scale ◽  
Response To Selection ◽  
Natural Genetic Variation ◽  
The Third ◽  
Scale Response

ABSTRACT The amount and form of natural genetic variation for recombination were studied in six lines for which second chromosomes were extracted from a natural population of Drosophila melanogaster. Multiply marked second, Χ and third chromosomes were used to score recombination. Recombination in the second chromosomes varied in both amount and distribution. These second chromosomes caused variation in the amount and distribution of crossing over in the Χ chromosome and also caused variation in the amount, but not the distribution, of crossing over in the third chromosome. The total amount of crossing over on a chromosome varied by 12-14%. One small region varied twofold; other regions varied by 16-38%. Lines with less crossing over on one chromosome generally had less crossing over on other chromosomes, the opposite of the standard interchromosomal effect. These results show that modifiers of recombination can affect more than one chromosome, and that the variation exists for fine-scale response to selection on recombination.

scholarly journals Inheritance of the Flower Types of Gerbera hybrida

2004 ◽  
Vol 129 (6) ◽  
pp. 802-810 ◽  
Author(s):  
Wesley E. Kloos ◽  
Carol G. George ◽  
Laurie K. Sorge
Keyword(s):  
North Carolina ◽  
Single Gene ◽  
Dominant Gene ◽  
Wild Type ◽  
Male Sterile ◽  
Gerbera Hybrida ◽  
The North ◽  
Wide Range ◽  
Segregation Ratios ◽  
Linkage Relationships

Cultivated gerbera daisies [Gerbera hybrida (G. jamesonii Bolus ex Adlam × G. viridifolia Schultz-Bip)] have several different flower types. They include single and crested cultivars that have normal florets with elliptical (ligulate) outer corolla lips and spider cultivars that have florets with laciniated (split) outer corolla lips appearing as several pointed lobes. The objective of this investigation was to determine the mode of inheritance of the major flower types of gerberas in the North Carolina State Univ. collection. The collection contained parents and four generations of progeny representing a wide range of single and crested cultivars and some spider cultivars. Genotypes of parents used in crosses were determined by testcrosses to single-flowered, ligulate floret cultivars similar in phenotype to the wild, parental gerbera species. Testcrosses indicated that the wild type was recessive to the crested and spider flower types and given the genotype crcrspsp. For each of the types, a series of crosses were made to produce PA, PB, F1, F2, BC1A, and BC1B progeny. Allelism was tested operationally by crossing genotypes in all possible combinations and observing single-gene-pair ratios. Linkage relationships among the crested and spider loci were tested using dihybrid crosses and testcrosses. Phenotypic segregation ratios suggested the presence of two dominant alleles, Crd and Cr, determining the enlarged disk and trans floret, male-sterile and enlarged trans floret, male-fertile crested types, respectively, and an unlinked dominant gene, Sp, determining the spider type. Dominance appeared to be incomplete due to the reduction of trans floret length in most Crdcr and Crcr heterozygotes compared to crested homozygotes and the appearance of the quasi-spider type (spider trans and disk florets and ligulate and/or slightly notched ray florets) among certain crested Spsp heterozygotes.

scholarly journals THE EFFECT OF RECOMBINATION-DEFECTIVE MEIOTIC MUTANTS ON FOURTH-CHROMOSOME CROSSING OVER IN DROSOPHILA MELANOGASTER

Genetics ◽  
1978 ◽  
Vol 90 (4) ◽  
pp. 699-712
Author(s):  
L Sandler ◽  
Paul Szauter
Keyword(s):  
Drosophila Melanogaster ◽  
Spatial Distribution ◽  
The Other ◽  
Crossing Over ◽  
Chromosome 4 ◽  
Wild Type ◽  
Fourth Chromosome ◽  
Meiotic Mutants ◽  
Other Hand

ABSTRACT Crossing over was measured on the normally achiasmate fourth chromosome in females homozygous for one of our different recombination-defective meiotic mutants. Under the influence of those meiotic mutants that affect the major chromosomes by altering the spatial distribution of exchanges, meiotic fourth-chromosome recombinants were recovered irrespective of whether or not the meiotic mutant decreases crossing over on the other chromosomes. No crossing over, on the other hand, was detected on chromosome 4 in either wild type or in the presence of a meiotic mutant that decreases the frequency, but that does not affect the spatial distribution, of exchange on the major chromosomes. It is concluded from these observations that (a) in wild type there are regional constraints on exchange that can be attenuated or eliminated by the defects caused by recombination-defective meiotic mutants; (b) these very constraints account for the absence of recombination on chromosome 4 in wild type; and (c) despite being normally achiasmate, chromosome 4 responds to recombination-defective meiotic mutants in the same way as do the other chromosomes.

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