MEIOTIC DRIVE IN NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER. IX. SUPPRESSORS OF SEGREGATION DISTORTER IN WILD POPULATIONS

1970 ◽  
Vol 12 (3) ◽  
pp. 594-600 ◽  
Author(s):  
D. L. Hartl

A population of Drosophila melanogaster in Madison, Wisconsin, has been screened for suppressors of segregation distorter (SD), an autosomal meiotic drive element found in the same population. Three kinds of suppressors were tested for: (1) Y-linked suppressors, none were found, (2) X-linked suppressors, whose frequency was found to be 85%, and (3) autosomal dominant suppressors, which occur in 45% of autosome complements.The frequency of X-linked suppressors is comparable to that found in a Japanese population; autosomal suppressors are much more frequent in Madison than in Japan (Katoaka, 1967). The similarity in the frequency of sex-linked suppressors may result from the meiotic drive shown by the suppressor-X itself; the difference in the frequency of autosomal dominant suppressors is possibly related to a higher frequency of SD itself in the Madison population.

Genetics ◽  
1996 ◽  
Vol 143 (4) ◽  
pp. 1675-1688 ◽  
Author(s):  
Michael F Palopoli ◽  
Chung-I Wu

Abstract Segregation Distorter (SD) is a system of meiotic drive found in natural populations of Drosophila melanogaster. Males heterozygous for an SD second chromosome and a normal homologue (SD  +) produce predominantly SD-bearing sperm. The coadapted gene complex responsible for this transmission advantage spans the second chromosome centromere, consisting of three major and several minor interacting loci. To investigate the evolutionary history of this system, we surveyed levels of polymorphism and divergence at six genes that together encompass this pericentromeric region and span seven map units. Interestingly, there was no discernible divergence between SD and SD  + chromosomes for any of these molecular markers. Furthermore, SD chromosomes harbored much less polymorphism than did SD  + chromosomes. The results suggest that the SD system evolved recently, swept to appreciable frequencies worldwide, and carried with it the entire second chromosome centromeric region (roughly 10% of the genome). Despite its well-documented genetic complexity, this coadapted system appears to have evolved on a time scale that is much shorter than can be gauged using nucleotide substitution data. Finally, the large genomic region hitchhiking with SD indicates that a multilocus, epistatically selected system could affect the levels of DNA polymorphism observed in regions of reduced recombination.


Genetics ◽  
1975 ◽  
Vol 80 (4) ◽  
pp. 807-819
Author(s):  
Takao K Watanabe ◽  
Seido Ohnishi

ABSTRACT Two hundred second chromosomes were extracted from a Japanese population in October of 1972, and the viabilities and productivities of homozygotes and heterozygotes from them were examined. Viability was measured by the Cy method and productivity by the number of progeny produced per female. The frequency of lethal-carrying chromosomes was 0.315. When the average heterozygote viability was standardized as 1.000, the average homozygote viability was 0.595 including the lethal lines, and 0.866 excluding them. The frequency of recessive sterile chromosomes among 131 non-lethal lines was 0.092 in females and 0.183 in males. There were two instances in which homozygosis for the second chromosome caused sterility in both sexes, which was close to the number expected (2.2) on a random basis of 0.092 × 0.183 × 131. When the average heterozygote productivity of 200 lines was standardized as 1.000, the average homozygote productivity was 0.532 including female steriles, and 0.584 excluding them. The ratio of detrimental load to lethal load was 0.383, while the ratio of partial sterility load to complete sterility load was 5.767. The average viability of lethal heterozygotes was slightly, but not significantly, lower than that of lethal-free heterozygotes, while the average productivity of lethal heterozygotes was significantly lower than that of lethal-free heterozygotes. There was a significant association of sterility in either sex with low viability of homozygotes. However, no statistically significant differences in viability and productivity were detected between sterile heterozygotes and non-sterile heterozygotes. The heterozygous effects of viability and productivity polygenes were examined by regressions of the heterozygotes on the sum of corresponding homozygotes. The regression coefficients were slightly positive for both viability and productivity if lethal and sterile chromosomes were excluded. The correlation between viability and productivity in homozygotes was significantly positive when sterile chromosomes were included, but the significance disappeared when the sterile chromosomes were excluded. In the heterozygotes there were no detectable correlations between them.


Genetics ◽  
1972 ◽  
Vol 72 (1) ◽  
pp. 105-115
Author(s):  
George L Gabor Miklos ◽  
Armon F Yanders ◽  
W J Peacock

ABSTRACT The behaviour of two "meiotic drive" systems, Segregation-Distorter (SD) and the sex chromosome sc4sc8 has been examined in the same meiocyte. It has been found that the two systems interact in a specific way. When the distorting effects of SD and sc4sc8 are against each other, there is no detectable interaction. Each system is apparently oblivious to the presence of the other, gametes being produced according to independence expectations. However when the affected chromosomes are at the same meiotic pole an interaction occurs; the survival probability of the gamete containing both distorted chromosomal products is increased, rather than being decreased by the combined action of two systems.


Genetics ◽  
1987 ◽  
Vol 115 (1) ◽  
pp. 143-151
Author(s):  
Andrew G Clark

ABSTRACT Functional variation among Y chromosomes in natural populations of Drosophila melanogaster was assayed by a segregation study. A total of 36 Y chromosomes was extracted and ten generations of replacement backcrossing yielded stocks with Y chromosomes in two different genetic backgrounds. Eleven of the Y chromosomes were from diverse geographic origins, and the remaining 25 were from locally captured flies. Segregation of sexes in adult offspring was scored for the four possible crosses among the two backgrounds with each Y chromosome. Although the design confounds meiotic drive and effects on viability, statistical partitioning of these effects reveals significant variation among lines in Y chromosome segregation. Results are discussed in regards to models of Y-linked segregation and viability effects, which suggest that Y-linked adaptive polymorphism is unlikely.


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