scholarly journals The Sex-Ratio Trait in Drosophila simulans: Genetic Analysis of Distortion and Suppression

Genetics ◽  
1997 ◽  
Vol 147 (2) ◽  
pp. 635-642 ◽  
Author(s):  
Michel Cazemajor ◽  
Claudie Landré ◽  
Catherine Montchamp-Moreau
Keyword(s):  
Sex Ratio ◽  
Genetic Analysis ◽  
High Frequency ◽  
Natural Populations ◽  
Meiotic Drive ◽  
Drosophila Simulans ◽  
Standard Strain ◽  
Large Excess ◽  
X Chromosomes ◽  
Naturally Occurring

The sex-ratio trait described in several Drosophila species is a type of naturally occurring X-linked meiotic drive that causes males bearing a sex-ratio  X chromosome to produce progenies with a large excess of females. We have previously reported the occurrence of sex-ratio X chromosomes in Drosophila simulans. In this species, because of the co-occurrence of drive suppressors, the natural populations and the derived laboratory strains show an equal sex-ratio even when sex-ratio X chromosomes are present at a high frequency. The presence of sex-ratio X chromosomes is established via crosses with a standard strain that is devoid of drive suppressors. In this article, we show first that the sex-ratio trait in D. simulans results from the action of several X-linked loci. Second we describe drive suppressors on each major autosome as well as on the Y chromosome. The Y-linked factors suppress the drive partially whereas the autosomal suppression can be complete.

Sex-ratio meiotic drive in Drosophila simulans: cellular mechanism, candidate genes and evolution

2006 ◽  
Vol 34 (4) ◽  
pp. 562-565 ◽  
Author(s):  
C. Montchamp-Moreau
Keyword(s):  
Sex Ratio ◽  
X Chromosome ◽  
Natural Populations ◽  
Meiotic Drive ◽  
Female Offspring ◽  
Drosophila Simulans ◽  
X Chromosomes ◽  
Individual Fitness ◽  
Primary Sex Ratio ◽  
Intragenomic Conflict

The sex-ratio trait, reported in a dozen Drosophila species, is a type of naturally occurring meiotic drive in which the driving elements are located on the X chromosome. Typically, as the result of a shortage of Y-bearing spermatozoa, males carrying a sex-ratio X chromosome produce a large excess of female offspring. The presence of sex-ratio chromosomes in a species can have considerable evolutionary consequences, because they can affect individual fitness and trigger extended intragenomic conflict. Here, I present the main results of the study performed in Drosophila simulans. In this species, the loss of Y-bearing spermatozoa is related to the inability of the Y chromosome sister-chromatids to separate properly during meiosis II. Fine genetic mapping has shown that the primary sex-ratio locus on the X chromosome contains two distorter elements acting synergistically, both of which are required for drive expression. One element has been genetically mapped to a tandem duplication. To infer the natural history of the trait, the pattern of DNA sequence polymorphism in the surrounding chromosomal region is being analysed in natural populations of D. simulans harbouring sex-ratio X chromosomes. Initial results have revealed the recent spread of a distorter allele.

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.

scholarly journals Polymorphism for Y-Linked Suppressors of sex-ratio in Two Natural Populations of Drosophila mediopunctata

Genetics ◽  
1997 ◽  
Vol 146 (3) ◽  
pp. 891-902 ◽  
Author(s):  
Antonio Bernardo Carvalho ◽  
Suzana Casaccia Vaz ◽  
Louis Bernard Klaczko
Keyword(s):  
Population Genetics ◽  
Population Dynamics ◽  
Natural Selection ◽  
Sex Ratio ◽  
Numerical Simulations ◽  
Natural Populations ◽  
Meiotic Drive ◽  
X Chromosomes ◽  
Variable Expression ◽  
Y Chromosomes

In several Drosophila species there is a trait known as “sex-ratio”: males carrying certain X chromosomes (called “SR”) produce female biased progenies due to X-Y meiotic drive. In Drosophila mediopunctata this trait has a variable expression due to Y-linked suppressors of sex-ratio expression, among other factors. There are two types of Y chromosomes (suppressor and nonsuppressor) and two types of SR chromosomes (suppressible and unsuppressible). Sex-ratio expression is suppressed in males with the SRsuppressible/Ysuppressor genotype, whereas the remaining three genotypes produce female biased progenies. Now we have found that ∼10–20% of the Y chromosomes from two natural populations 1500 km apart are suppressors of sex-ratio expression. Preliminary estimates indicate that Ysuppressor has a meiotic drive advantage of 6% over Ynonsuppressor. This Y polymorphism for a nonneutral trait is unexpected under current population genetics theoly. We propose that this polymorphism is stabilized by an equilibrium between meiotic drive and natural selection, resulting from interactions in the population dynamics of X and Y alleles. Numerical simulations showed that this mechanism may stabilize nonneutral Y polymorphisms such as we have found in D. mediopunctata.

scholarly journals Sex Chromosome Meiotic Drive in Stalk-Eyed Flies

Genetics ◽  
1997 ◽  
Vol 147 (3) ◽  
pp. 1169-1180 ◽  
Author(s):  
Daven C Presgraves ◽  
Emily Severance ◽  
Gerald S Willrinson
Keyword(s):  
Sex Ratio ◽  
Sex Chromosome ◽  
Sex Ratios ◽  
Natural Populations ◽  
Meiotic Drive ◽  
Operational Sex Ratio ◽  
Genetic Modifiers ◽  
Ratio Distortion ◽  
The Impact ◽  
Sex Ratio Distortion

Meiotically driven sex chromosomes can quickly spread to fixation and cause population extinction unless balanced by selection or suppressed by genetic modifiers. We report results of genetic analyses that demonstrate that extreme female-biased sex ratios in two sister species of stalk-eyed flies, Cyrtodiopsis dalmanni and C. whitei, are due to a meiotic drive element on the X chromosome (Xd). Relatively high frequencies of Xd in C. dalmanni and C. whitei (13–17% and 29%, respectively) cause female-biased sex ratios in natural populations of both species. Sex ratio distortion is associated with spermatid degeneration in male carriers of Xd. Variation in sex ratios is caused by Y-linked and autosomal factors that decrease the intensity of meiotic drive. Y-linked polymorphism for resistance to drive exists in C. dalmanni in which a resistant Y chromosome reduces the intensity and reverses the direction of meiotic drive. When paired with Xd, modifying Y chromosomes (Ym) cause the transmission of predominantly Y-bearing sperm, and on average, production of 63% male progeny. The absence of sex ratio distortion in closely related monomorphic outgroup species suggests that this meiotic drive system may predate the origin of C. whitei and C. dalmanni. We discuss factors likely to be involved in the persistence of these sex-linked polymorphisms and consider the impact of Xd on the operational sex ratio and the intensity of sexual selection in these extremely sexually dimorphic flies.

scholarly journals SEX RATIO DISTORTION CAUSED BY MEIOTIC DRIVE IN A MOSQUITO, Culex pipiens L

Genetics ◽  
1978 ◽  
Vol 88 (3) ◽  
pp. 427-446
Author(s):  
Theresa Luine Sweeny ◽  
A Ralph Barr
Keyword(s):  
Sex Ratio ◽  
Chromosome Pair ◽  
Culex Pipiens ◽  
Recessive Gene ◽  
Meiotic Drive ◽  
Female Offspring ◽  
Large Excess ◽  
Daughter Cells ◽  
Ratio Distortion ◽  
Sex Ratio Distortion

ABSTRACT A genetic factor, distorter (d), has been discovered that upsets the normal sex ratio of 1:1 and results in a large excess of males in Culex pipiens. The effect can be explained by a sex-linked, recessive gene. Males homozygous for the gene (Md/md) produce few female offspring; the effect is not due to postzygotic mortality. During the first meiotic division in spermatogenesis, the shortest chromosome pair, which, according to Jost and Laven (1971), is associated with sex determination, can be seen to be abnormal. In a high proportion of spermatocysts, one of the dyads of the shortest bivalent fragments, and the pieces are distributed irregularly to the daughter cells. It is believed that the female-determining chromosomes fragment. This would give rise to an excess of male-determining sperm. The possible usefulness of this factor for control or for experimental purposes is discussed.

scholarly journals Sex ratios in natural populations of Drosophila pseudoobscura from Mexico

Genetika ◽  
2012 ◽  
Vol 44 (3) ◽  
pp. 491-498 ◽  
Author(s):  
Victor Salceda ◽  
Carolina Arceo-Maldonado
Keyword(s):  
Sex Ratio ◽  
Sex Chromosome ◽  
Natural Populations ◽  
Diploid Species ◽  
Drosophila Pseudoobscura ◽  
Adult Offspring ◽  
Equal Proportion ◽  
X Chromosomes ◽  
The Individual ◽  
Number Of Males

Most species show an equal proportion of individuals of both sexes. In diploid species sex ratio is determined by a genic balance between sex chromosomes. In Drosophila sex is determined by the ratio of X- chromosomes versus autosomes and in some species of the genus it is related to the presence of an inversion in the sex chromosome. The present work analyses the sex ratio in 27 natural populations of Drosophila pseudoobscura that inhabit Mexico. Female flies captured in nature were counted and their sex ratio calculated and been called generation P, then cultured individualy, allowed to leave adult offspring which was quantified in order to get its sex ratio and designated generation F1. sex ratio was calculated using the expression: number of males times 100 divided by the number of females proposed by Darwin (1871). The sex ratio of each population was taken using the average of all the individual counts from each sample. The values found varied among different generations and populations, so for generation P their values varieded 37.4 to 190.4 and in generation F1 from 31.3 up to 96.4 males for each 100 females. According to their geographical distribution four North to South transects were arranged and in them means varied from 60.8 to 81.7 males for each 100 females. All this means that in Mexican population are more females than males, exceptionally more males than females.

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.

scholarly journals Selective Sweeps in a 2-Locus Model for Sex-Ratio Meiotic Drive in Drosophila simulans

2007 ◽  
Vol 25 (2) ◽  
pp. 409-416 ◽  
Author(s):  
Nicolas Derome ◽  
Emmanuelle Baudry ◽  
David Ogereau ◽  
Michel Veuille ◽  
Catherine Montchamp-Moreau
Keyword(s):  
Sex Ratio ◽  
Meiotic Drive ◽  
Drosophila Simulans ◽  
Selective Sweeps ◽  
Locus Model

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 Theoretical consequences of the Mutagenic Chain Reaction for manipulating natural populations

2015 ◽  
Author(s):  
Robert Unckless ◽  
Philipp Messer ◽  
Andrew Clark
Keyword(s):  
Critical Point ◽  
High Frequency ◽  
Natural Populations ◽  
Meiotic Drive ◽  
Fitness Cost ◽  
Chain Reaction ◽  
Internal Equilibrium ◽  
Rapid Fixation ◽  
Genetic Technologies ◽  
Mutagenic Chain Reaction

The use of recombinant genetic technologies for population manipulation has mostly remained an abstract idea due to the lack of a suitable means to drive novel gene constructs to high frequency in populations. Recently Gantz and Bier showed that the use of CRISPR/Cas9 technology could provide an artificial drive mechanism, the so-called Mutagenic Chain Reaction (MCR), which could lead to rapid fixation of even a deleterious introduced allele. We establish the equivalence of this system to models of meiotic drive and review the results of simple models showing that, when there is a fitness cost to the MCR allele, an internal equilibrium exists that is usually unstable. Introductions must be at a frequency above this critical point for the successful invasion of the MCR allele. These modeling results have important implications for application of MCR in natural populations.

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