COMPONENTS OF SELECTION IN X CHROMOSOME LINES OF DROSOPHILA MELANOGASTER: SEX RATIO MODIFICATION BY MEIOTIC DRIVE AND VIABILITY SELECTION

Genetics ◽  
1984 ◽  
Vol 108 (4) ◽  
pp. 941-952
Author(s):  
James W Curtsinger
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Maximum Likelihood ◽  
Sex Ratio ◽  
Genetic Background ◽  
Likelihood Estimation ◽  
Meiotic Drive ◽  
Mendelian Segregation ◽  
Viability Selection ◽  
Naturally Occurring

ABSTRACT Selection coefficients and segregation parameters have been estimated in 18 randomly chosen lines carrying wild Χ chromosomes on the cn bw genetic background. Each line was studied in replicated crosses of four types, with approximately 100 replications per line per cross. Crosses in which male Χ chromosomes differed exhibited significant sex ratio heterogeneity. Maximum likelihood estimation of segregation parameters revealed two lines in which the proportion of Χ-bearing gametes produced by males was significantly different from Mendelian expectations. These observations suggest that segregation distortion is a common feature of naturally occurring genetic variation. Non-Mendelian segregation has important evolutionary implications.

EVIDENCE FOR EXTENSIVE GENETIC DIFFERENTIATION BETWEEN THE SEX-RATIO AND THE STANDARD ARRANGEMENT OF DROSOPHILA PSEUDOOBSCURA AND D. PERSIMILIS AND IDENTIFICATION OF HYBRID STERILITY FACTORS

Genetics ◽  
1983 ◽  
Vol 105 (1) ◽  
pp. 71-86
Author(s):  
Chung-I Wu ◽  
Andrew T Beckenbach
Keyword(s):  
Sex Ratio ◽  
Genetic Differentiation ◽  
Genetic Background ◽  
Hybrid Sterility ◽  
Strong Support ◽  
Meiotic Drive ◽  
Complete Loss ◽  
Drosophila Pseudoobscura ◽  
Drosophila Persimilis ◽  
Standard Arrangement

ABSTRACT This study deals with sex-ratio genes tightly linked within the Sex-Ratio inversion. By taking advantage of the fact that the Sex-Ratio chromosome of Drosophila persimilis [SR(B)] is homosequential to the Standard chromosome of D. pseudoobscura [ST(A)], we carried out two reciprocal introgression experiments. Individual segments of SR(B) or ST(A) were introgressed into the genome of D. pseudoobscura or D. persimilis, respectively. Males possessing a hybrid SR(B)-ST(A) X chromosome and a genetic background derived from either of the two species were tested for fertility and sex-ratio expression.—It was found that, in terms of the meiotic drive genes, the Sex-Ratio chromosome differs extensively from the Standard chromosome. Because recombinations of these genes result in a complete loss of sex-ratio expression, this finding lends strong support to the hypothesis of gene coadaptation. Coadaptation, in this context, is the advantage of being transmitted preferentially. In light of this finding, the evolution of the sex-ratio system in these two sibling species is discussed.—Introgression experiments also yielded information about hybrid sterility. With reciprocal introgression, sterility interactions were found to be "asymmetric." The asymmetry is fully expected from the viewpoint of evolution of postmating reproductive isolation.

scholarly journals Genetic Variation in Rates of Nondisjunction: Association of Two Naturally Occurring Polymorphisms in the Chromokinesin nod With Increased Rates of Nondisjunction in Drosophila melanogaster

Genetics ◽  
1999 ◽  
Vol 152 (4) ◽  
pp. 1605-1614 ◽  
Author(s):  
Michael E Zwick ◽  
Jennifer L Salstrom ◽  
Charles H Langley
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Chromosome Segregation ◽  
Natural Populations ◽  
Intermediate Frequency ◽  
Female Meiosis ◽  
X Chromosomes ◽  
Naturally Occurring ◽  
High Level ◽  
Female Specific

Abstract Genetic variation in nondisjunction frequency among X chromosomes from two Drosophila melanogaster natural populations is examined in a sensitized assay. A high level of genetic variation is observed (a range of 0.006-0.241). Two naturally occurring variants at the nod locus, a chromokinesin required for proper achiasmate chromosome segregation, are significantly associated with an increased frequency of nondisjunction. Both of these polymorphisms are found at intermediate frequency in widely distributed natural populations. To account for these observations, we propose a general model incorporating unique opportunities for meiotic drive during female meiosis. The oötid competition model can account for both high mean rates of female-specific nondisjunction in Drosophila and humans as well as the standing genetic variation in this critical fitness character in natural populations.

scholarly journals Are Unpaired Chromosomes Spermicidal?: A Maximum-Likelihood Analysis of Segregation and Meiotic Drive in Drosophila melanogaster Males Deficient for the Ribosomal-DNA

Genetics ◽  
1999 ◽  
Vol 151 (1) ◽  
pp. 251-262 ◽  
Author(s):  
Leonard G Robbins
Keyword(s):  
Drosophila Melanogaster ◽  
Maximum Likelihood ◽  
Physical State ◽  
Meiotic Drive ◽  
Direct Connection ◽  
Maximum Likelihood Analysis ◽  
Likelihood Analysis ◽  
Sperm Development ◽  
Sperm Survival ◽  
Sperm Chromosomes

AbstractMeiosis in Drosophila melanogaster males is achiasmate and requires special systems to ensure normal segregation. Several situations that yield frequent nondisjunction also produce high levels of chromatin-dependent sperm lethality, suggesting the possibility of a simple and direct connection between defective disjunction and defective sperm development. One hypothesis that has been offered is that pairing not only ensures disjunction, but also changes the physical state of chromosomes so that they can be packaged in sperm. Here, I present an analysis of extensive data on disjunction and sperm survival in rDNA-deficient males collected by B. McKee and D. Lindsley. This analysis demonstrates that, although nondisjunction and sperm lethality are indeed correlated, the basis of this is not the presence of unpaired chromosomes in the sperm. Chromosomes that have failed to disjoin are not themselves spermicidal.

scholarly journals On the components of segregation distortion in Drosophila melanogaster. V. Molecular analysis of the Sd locus.

Genetics ◽  
1991 ◽  
Vol 129 (1) ◽  
pp. 133-144 ◽  
Author(s):  
P A Powers ◽  
B Ganetzky
Keyword(s):  
Drosophila Melanogaster ◽  
Sequence Analysis ◽  
Molecular Analysis ◽  
Tandem Duplication ◽  
Meiotic Drive ◽  
Northern Blots ◽  
Sequence Identity ◽  
Naturally Occurring ◽  
Segregation Distorter ◽  
Genomic Probes

Abstract Segregation Distorter (SD) is a naturally occurring meiotic drive system comprising at least three distinct loci: Sd, Rsp and E(SD). Heterozygous SD/SD+ males transmit the SD chromosome in vast excess over the normal homolog. The distorted transmission involves the induced dysfunction of the spermatids that receive the SD+ chromosome. In the 220-kb region of DNA that contains the Sd gene, we identified a 5-kb tandem duplication that is uniquely associated with all SD chromosomes, absent in SD+ chromosomes, and detectably altered in Sd revertants. On northern blots, genomic probes from the tandem duplication detect an SD-specific 4-kb transcript in addition to several smaller transcripts present in both SD and SD+. Seven classes of cDNAs derived from these transcripts have been isolated. All of these cDNAs share extensive sequence identity at their 3' ends but differ at their 5' ends. Sequence analysis indicates that these cDNAs potentially encode four distinct, but related, polypeptides. Introduction of the tandem duplication into SD+ flies by germline transformation did not confer the dominant gain-of-function Sd phenotype. This result, taken together with our analysis of the Sd cDNAs, suggests that the duplication is part of a much larger gene that encodes several different polypeptides.

scholarly journals An Experimental Demonstration of Fisher's Principle: Evolution of Sexual Proportion by Natural Selection

Genetics ◽  
1998 ◽  
Vol 148 (2) ◽  
pp. 719-731
Author(s):  
Antonio Bernardo Carvalho ◽  
Michelle Cristina Sampaio ◽  
Flavia Roque Varandas ◽  
Louis Bernard Klaczko
Keyword(s):  
Natural Selection ◽  
Genetic Variability ◽  
Sex Ratio ◽  
Reproductive Effort ◽  
Meiotic Drive ◽  
Experimental Demonstration ◽  
Biological Phenomenon ◽  
Naturally Occurring ◽  
Experimental Populations ◽  
Fisher’S Principle

Abstract Most sexually reproducing species have sexual proportions around 1:1. This major biological phenomenon remained unexplained until 1930, when Fisher proposed that it results from a mechanism of natural selection. Here we report the first experimental test of his model that obeys all its assumptions. We used a naturally occurring X-Y meiotic drive system—the sex-ratio trait of Drosophila mediopunctata—to generate female-biased experimental populations. As predicted by Fisher, these populations evolved toward equal sex proportions due to natural selection, by accumulation of autosomal alleles that direct the parental reproductive effort toward the rare sex. Classical Fisherian evolution is a rather slow mechanism: despite a very large amount of genetic variability, the experimental populations evolved from 16% of males to 32% of males in 49 generations and would take 330 generations (29 years) to reach 49%. This slowness has important implications for species potentially endangered by skewed sexual proportions, such as reptiles with temperature sex determination.

scholarly journals Unusual genetic architecture of natural variation affecting drug resistance in Drosophila melanogaster

2002 ◽  
Vol 80 (3) ◽  
pp. 205-213 ◽  
Author(s):  
ROLAND CARRILLO ◽  
GREG GIBSON
Keyword(s):  
Drug Resistance ◽  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Genetic Architecture ◽  
Natural Variation ◽  
Starvation Resistance ◽  
Female Resistance ◽  
Caffeine Ingestion ◽  
Naturally Occurring ◽  
Chronic Ingestion

Naturally occurring genetic variation was quantified for survival time of adult Drosophila melanogaster exposed to chronic ingestion of the drugs nicotine, caffeine, dopamine, tyramine and octopamine. Responses to nicotine, tyramine and octopamine were genetically correlated in both sexes, whereas caffeine response correlated with starvation resistance. However, there is also genetic variation that is specific for each of the drugs. Females tended to be more resistant than males to nicotine and caffeine but sex-by-genotype interactions were also seen for these drugs and for the response to dopamine. An unusual and complex genetic architecture was observed in crosses between lines with different responses to caffeine ingestion. Additive and dominance components were clearly seen from the analysis of F1 individuals, but increased female resistance to caffeine in backcross generations and increased male sensitivity in F2 generations confused the interpretation of possible epistatic contributions.

scholarly journals Sex-ratio Meiotic Drive in Drosophila simulans Is Related to Equational Nondisjunction of the Y Chromosome

Genetics ◽  
2000 ◽  
Vol 154 (1) ◽  
pp. 229-236
Author(s):  
Michel Cazemajor ◽  
Dominique Joly ◽  
Catherine Montchamp-Moreau
Keyword(s):  
Sex Ratio ◽  
Y Chromosome ◽  
Direct Evidence ◽  
Sex Chromosome ◽  
Meiotic Drive ◽  
Female Offspring ◽  
Drosophila Simulans ◽  
Common Basis ◽  
Naturally Occurring

Abstract The sex-ratio trait, an example of naturally occurring X-linked meiotic drive, has been reported in a dozen Drosophila species. Males carrying a sex-ratio X chromosome produce an excess of female offspring caused by a deficiency of Y-bearing sperm. In Drosophila simulans, such males produce ~70–90% female offspring, and 15–30% of the male offspring are sterile. Here, we investigate the cytological basis of the drive in this species. We show that the sex-ratio trait is associated with nondisjunction of Y chromatids in meiosis II. Fluorescence in situ hybridization (FISH) using sex-chromosome-specific probes provides direct evidence that the drive is caused by the failure of the resulting spermatids to develop into functional sperm. XYY progeny were not observed, indicating that few or no YY spermatids escape failure. The recovery of XO males among the progeny of sex-ratio males shows that some nullo-XY spermatids become functional sperm and likely explains the male sterility. A review of the cytological data in other species shows that aberrant behavior of the Y chromosome may be a common basis of sex-ratio meiotic drive in Drosophila and the signal that triggers differential spermiogenesis failure.

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