Scholarly Literature
This is an aggregation of scholarly literature from peer-reviewed journals, bioRxiv , medRxiv and arXiv preprint servers focused on natural and engineered selfish genetic elements and genetic biocontrol. New citations are added as they appear. This content is intended for anyone interested in the scholarly literature on gene drive and genetic biocontrol.
Methods for replacement of malaria vector populations
4464Curtis, CFG, P. M., American Journal of Tropical Medicine and Hygiene, 91:43-48. 1988-01-02 00:00:00.
The prospects are reviewed of replacement of malaria vector populations by harmless mosquito populations by means of: (i) ecologically competitive non-vector species; (ii) natural selection due to the harmfulness of being infected; (iii) selection for insecticide resistance genes; (iv) meiotic drive; (v) negative heterosis; and (vi) hybrid dysgenesis. Serious difficulties exist with all of these approaches. At present 'dilution', i.e. release of insects carrying the desired genes without any system for forcing population replacement is the only available method. It avoids the disadvantage that, in constructing elaborate genetic 'packages', factors for low fitness may be irreversibly incorporated into them. It is debatable whether release of males only or both sexes should be attempted.
Thte genetic basis of resistance and sensitivity to the meiotic drive gene D in the mosquito Aedes aegypti L.
4469Wood, RJO, N. A., Genetica, 72:69-79. 1987-01-07 00:00:00.
A study has been made on the genetic basis of meiotic drive at the Distorter (D) locus which, in coupling with the male-determining gene (or region) M on the Y chromosome, causes production of excess male progeny. Its effect is regulated by the sensitivity/resistance of the X chromosome. This study demonstrates that there are two major loci controlling resistance/sensitivity to MD: (1) the m gene (or region) on the X chromosome (allelic with M) which may be either m R or m S (resistant or sensitive), (2) the t (tolerance) gene (or genes) which recombines with m and, if present, largely counteracts the effect of m S . There is also evidence that MD itself is capable of limited adaptation.; ; The conclusions were derived from using MD males of the T30 or ACCRA strains (from Trinidad and Ghana respectively). The work involved the use of the CHIPEI and RED strains with sensitive X chromosomes, the latter also carrying the t (tolerance) gene which is linked to re (red eye) and m (the sex-determining locus or region) but recombines with both. The implications of these findings for using MD as a method of population control are discussed.
Abnormal salivary gland puff associated with meiotic drive in mosquitos (Diptera, Culicidae)
4468Sweeny, TLG, P.; Barr, A. R., Journal of Medical Entomology, 24:623-627. 1987-01-06 00:00:00.
A meiotic drive factor, distorter (d), has been described previously for Culex pipiens L. mosquitoes. Males homozygous for the gene (Md/md) produce few female offspring owing to breakage of the female-determining dyad of chromosome 1 (the sex chromosome) during the first meiotic division of spermatogenesis. Orcein squash preparations of polytene salivary gland chromosomes of the distorter strain revealed a chromosome break and other abnormalities at zone 10C3, the location of a large puff that has been reported to be associated with sex determination in C. pipiens. In the polytene chromosomes, d apparently disrupts normal expansion and contraction of the puff. Zone 10C3 probably is also the breakpoint of the female-determining dyad. Zone 10C3 on the male-determining dyad seems to be resistant to the action of d, whereas zone 10C3 on the female-determining dyad is vulnerable to the destructive action of d. Possibly the break in the female-determining dyad occurs directly at m, the gene locus for "femaleness" in C. pipiens, in which case d may be a mutated form of m.
Control of meiotic drive of B-chromosomes in the mealybug, Pseudococcus affinis (obscurus)
4467Nur, UB, B. L. H., Genetics, 115:499-510. 1987-01-05 00:00:00.
Isofemale lines of Pseudococcus affznis (MASKELL) differ in their ability to maintain B chromosomes (Bs) due to the presence of genotypes that affect the rate of transmission (k) of the Bs. The nature of these genotypes was analyzed by comparing ks of males carrying the same B and the same paternal genome (which is heterochromatic), but differing in their maternal genome. In males from line L-60, which maintained the B at a frequency of over 4.0 Bs per individual, the mean k varied between 0.7 and 0.95 in different experiments. Over the same period, the mean k of males with a maternal genome from one of two lines in which the B was rapidly lost (L-1 19), increased from 0.5 to 0.9, and that of the other line (L-230) decreased gradually from 0.6 to less than 0.1. The ks appear not to be correlated with the geographical or parental origin of the B. The observed changes in k are attributed at least in part to changes in the frequency of genotypes (alleles) which can drastically reduce the transmission of the B and, when present in high frequency, can lead to its rapid loss. The frequency distribution of the ks of sons of F, females from the cross L-230 X L-60 suggests that the two lines differ at two unlinked loci with additive effects on k. The genome of L-119 also caused the B to undergo nondisjunction in about 10% of the primary spermatocytes. A comparison between the ks of the males tested and those of males from a natural population suggests that in that population the B is “parasitic” and that the frequency of transmission-reducing genotypes is low.
X-4 Translocation and meiotic drive in Drosophila melanogaster males: Role of sex chromosome pairing
4466McKee, B, Genetics, 116:409-413. 1987-01-04 00:00:00.
Males carrying certain X-4 translocations exhibit strongly skewed sperm recovery ratios. The Xp4D half of the translocation disjoins regularly from the Y chromosome and the 4‘XD half disjoins regularly from the normal 4. Yet the smaller member of each bivalent is recovered in excess of its pairing partner, apparently due to differential gametic lethality. Chromosome recovery probabilities are multiplicative; the viability of each genotype is the product of the recovery probability of its component chromosomes. Meiotic drive can also be caused by deficiency for X heterochromatin. In( I)scQLscBR males show the same size dependent chromosome recoveries and multiplicative recovery probabilities found in T(1;4)Bs males. Meiotic drive in Zn(I)scQLscBR males has been shown to be due to X-Y pairing failure. Although pairing is regular in the T(X;4) males, the striking phenotypic parallels suggest a common explanation. The experiments described below show that the two phenomena are, in fact, one and the same. X-4 translocations are shown to have the same effect on recovery of independently assorting chromosomes as does Zn(I)scqLscgR. Addition of pairing sites to the 4pXD half of the translocation eliminates drive. A common explanation-failure of the distal euchromatic portion of the X chromosome to participate in XY meiotic pairing-is suggested as the cause for drive. The effect of X chromosome breakpoint on X-4 translocation induced meiotic drive is investigated. It is found that translocations with breakpoints distal to 13C on the salivary map do not cause drive while translocations broken proximal to 13C cause drive. The level of drive is related to the position of the breakpoint-the more proximal the breakpoint the greater the drive.
Meiotic drive in the sex-chromosome system of the varying lemming, Dicrostonyx torquatus Pall (Rodentia, Microtinae)
4465Gileva, EA, Heredity, 59:383-389. 1987-01-03 00:00:00.
In the varying lemming, numerous fertile XY females occur regularly due to the X-linked mutation (X*). Their frequency both in natural populations and laboratory colonies turned out to be about twice higher than that expected under random segregation of heterochromosomes in both sexes. It has been shown in experiments that an excess of XY females resulted from a preferential segregation of the Y chromosome in males. Segregation distortion is not produced by selective embryonal mortality. Meiotic drive of the Y chromosome also causes a significant decrease of sex ratio. Although in the varying lemming meiotic drive is rather weak (the segregation ratio of the Y being 0·54–0·59), it seems to contribute essentially to the evolutionary spread and the maintenance of the X* mutation in populations. The example of Dicrostonyx and probably of other microtines also demonstrates the possible role of meiotic drive in the regulation of the population sex ratio in mammals.
The eradication of Glossina-palpalis-palpalis (Robineau-Desvoidy) (diptera, Glossinidae) using traps, insecticide-impregnated targets and the sterile insect technique in central Nigeria
26155W. Takken, M. A. Oladunmade, L. Dengwat, H. U. Feldmann, J. A. Onah, S. O. Tenabe and H. J. Hamann, Bulletin of Entomological Research, 76:275-286. 1986-06-01 13:33:24.
The integrated use of biconical traps, insecticide-impregnated targets and the sterile insect technique was developed for the eradication of Glossina palpalis palpalis (Robineau-Desvoidy) in a 1500-km2 area of central Nigeria. Six weeks or more of continuous removal trapping, using biconical traps, reduced the target tsetse population by more than 90% but failed to eradicate it. Males sterilized by irradiation from a ^Co source that were then released weekly induced significant sterility in target females and were successful in helping to eradicate the target population. A minimum ratio of 10:1 of sterile to wild males was required to achieve eradication in a central area of 300 km2. In marginal habitats, insecticide-impregnated targets were found adequate to control the tsetse population. The targets were also efficient as barriers to prevent reinvasion of the area. The combined effect of removal trapping and sterile male release is expected to eradicate G. p. palpalis from the entire study area.
Detection of Rsp and modifier variation in the meiotic drive system Segregation Distorter (SD) of Drosophila melanogaster
4470Lyttle, TWB, J. G.; Ganetzky, B., Genetics, 114:183-202. 1986-01-08 00:00:00.
Identification of allelic variability at the two major loci (Sd and Rsp) that interact to cause sperm dysfunction in Segregation distorter (SD) males of D. melanogaster has been hampered by the difficulty in separating the elements recombinationally. In addition, small differences in the strength of Sd alleles or sensitivities of Rsp alleles to Sd are difficult to measure against background genetic or environmental variation. Viability effects of the markers used to score progeny classes may also introduce a bias. Removal of Sd and E(SD) from their second chromosome location to create a Dp(2;Y)Sd E(SD) chromosome eliminates these problems, since any combination of Rsp alleles can be easily tested without resorting to recombinational techniques. Further, since these pairs of Rsp alleles are compared in their response to Dp Sd E(SD) in the same individual males, background variation and viability effects can be easily removed to allow finescale resolution of Rsp differences. Tests of all possible pairwise combination of six laboratory chromosomes in this way revealed at least three and possibly four different Rsp allelic classes. In addition, the hierarchical nature of the tests further allowed for determination of the presence of linked suppressors or enhancers of Sd activity. A sample of 11 second chromosomes selected from a group recently isolated from a natural population was also unambiguously ordered as to Rsp allelic status using this approach. The resultant pattern was similar to that obtained for the laboratory chromosomes, except for the not unexpected observation that the natural population apparently harbored more drive suppressors. The pattern of results obtained from these pairwise combinations of Rsp alleles supports the notion that there are no dominance interactions within the group, but that each responds more or less independently to Sd in giving sperm dysfunction.
Tthe genetic control of meiotic drive acting on the B-chromosome of Myrmeleotettix maculatus (Orthoptera, Aacrididae)
4473Shaw, MWH, G. M., Heredity, 54:187-194. 1985-01-11 00:00:00.
Crosses between populations with and without B-chromosomes were made, and backcrossed to the non B parent for two generations. No polygenic differences in male or female meiotic transmission were found, but a modifier of meiotic drive segregated in the experiment, drastically reducing female transmission rate. We tentatively interpret this as evidence of a coevolutionary race between the B-chromosome and the A genome.
Polymorphism in the rates of meiotic drive acting on the B-chromosome of Myrmeleotettix maculatus
4472Shaw, MWH, G. M.; Anderson, D. A., Heredity, 55:61-68. 1985-01-10 00:00:00.
A survey of all the available data on meiotic transmission rates in M. maculatus suggests that a polymorphism in female transmission rate exists in most natural populations. Differences in the frequency of the types or in the transmission rates they manifest may exist between populations or over time, but the evidence is not compelling. The data on males are also equivocal, especially because the environment may affect male transmission rate. We suggest that the polymorphism in female rates may demonstrate the selective equilibrium between the B and the genome in which it exists.
Genotypes suppressing meiotic drive of a B-chromosome in the mealybug, Pseudococcus obscurus
4471Nur, UB, B. L. H., Genetics, 110:73-92. 1985-01-09 00:00:00.
The rate of transmission (k) of a supernumerary B chromosome in male mealybugs is shown tq depend strongly on the chromosome set of materpal origin. When both parents came from an isofemale line in which the frequency of the B chromosome increased rapidly and stabilized at a mean of more than 4.0 B chromosomes per individual, was 0,92 and 0.95 in two series of crosses. However, when the female parent came from one of two isofemale lines in which the frequency of the B chromosome decreased from 2.0 to 0 in a few generations, R ranged from 0.53 to 0.78. The high ks, which represent a strong meiotic drive, are apparently responsible for the observed increase in the frequency of the B chromosome in several lines from a mean of about 0.5 to more than 4.0 in about 20 generations. The rapid loss of the B chromosome in other lines is attributed to genetic factors which caused the reduction in the rate of transmission qf the B chromosome.
Sex-chromosome meiotic drive in Drosophila melanogaster males
4474McKee, B, Genetics, 106:403-422. 1984-01-12 00:00:00.
In Drosophila melanogaster males, deficiency for X heterochromatin causes high X-Y nondisjunction and skewed sex chromosome segregation ratios (meiotic drive). Y and XY classes are recovered poorly because of sperm dysfunction. In this study it was found that X heterochromatic deficiencies disrupt recovery not only of the Y chromosome but also of the X and autosomes, that; both heterochromatic and euchromatic regions of chromosomes are affected and that the "sensitivity" of a chromosome to meiotic drive is a function of its length. Two models to explain these results are considered. One is a competitive model that proposes that all chromosomes must compete for a scarce chromosome-binding material in Xh- males. The failure to observe competitive interactions among chromosome recovery probabilities rules out this model. The second is a pairing model which holds that normal spermiogenesis requires X-Y pairing at special heterochromatic pairing sites. Unsaturated pairing sites become gametic lethals. This model fails to account for autosomal sensitivity to meiotic drive. It is also contradicted by evidence that saturation of Y-pairing sites fails to suppress meiotic drive in Xh- males and that extra X-pairing sites in an otherwise normal male do not induce drive. It is argued that meiotic drive results from separation of X euchromatin from X heterochromatin.
Integration of insect sterility and insecticides for control of Glossina morsitans morsitans Westwood (Diptera: Glossinidae) in Tanzania. IV. Application of endosulfan as an aerosol prior to release of sterile males
26520D. L. Williamson, D. A. Dame, C. W. Lee, D. B. Gates and P. E. Cobb, Bulletin of Entomological Research, 73:383-389. 1983-07-07 13:20:11.
As part of a programme to test the sterile insect technique against Glossina morsitans morsitans Westw. in Tanzania, two aerial applications of endosulfan were applied to a 195-km2 test area. The applications were made with a 28-day interval to provide an initial reduction in the target species prior to the release of sterile males. A Cessna 310 aircraft equipped with a rotary atomiser and operating at night was used to apply the insecticide at a dosage of about 20 g/ha. Flyround surveys within 48 h following the spraying operations indicated that a 100% reduction of G. m. morsitans adults was achieved in both applications, while G. pallidipes Aust. was reduced by 91 5% in the first and 100% in the second.
The fate of autosomeal modifiers of the sex-ratio trait in Drosophila and other sex-linked meiotic drive systems.
4475Wu, CI, Theoretical Population Biology, 24:107-120. 1983-01-13 00:00:00.
A model is proposed to analyze the behavior of autosomal suppressor modifiers of "Sex-Ratio" meiotic drive in drosophila. These modifiers, if neutral in fitness, are expected to increase because they tend to be associated with the rare sex (males). However, selection operating on the sex-linked drive locus will sometimes act against autosomal modifiers as well because the two loci are always in gametic phase disequilibrium. Conditions under which modifiers will not increase are presented in terms of the relative fitness of the sex-linked drive locus. To prevent the increase of modifiers, the fitness of Sex-Ratio males relative to Standard males has to be no greater than 0.3 and there has to be overdominance in females. This model integrates findings from the search for modifiers and results from the measurement of fitness.
Genetic-transformation of Drosophila with transposable element vectors
6252G. M. Rubin and A. C. Spradling, Science, 218:348-353. 1982-10-22 19:25:36.
Exogenous DNA sequences were introduced into the Drosophila germ line. A rosy transposon (ry1), constructed by inserting a chromosomal DNA fragment containing the wild-type rosy gene into a P transposable element, transformed germ line cells in 20 to 50 percent of the injected rosy mutant embryos. Transformants contained one or two copies of chromosomally integrated, intact ry1 that were stably inherited in subsequent generations. These transformed flies had wild-type eye color indicating that the visible genetic defect in the host strain could be fully and permanently corrected by the transferred gene. To demonstrate the generality of this approach, a DNA segment that does not confer a recognizable phenotype on recipients was also transferred into germ line chromosomes.
A cage replacement experiment involving introduction of genes for refractoriness to Plasmodium-yoelii-nigeriensis into a population of Anopheles gambiae (Diptera, Culicidae)
6230P. M. Graves and C. F. Curtis, Journal of Medical Entomology, 19:127-133. 1982-03-24 21:46:47.
A caged population of Anopheles gambiae was allowed to breed continuously and samples of the progeny were tested for susceptibility to Plasmodium yoelii nigeriensis. Males of a strain partially refractory to this parasite were released into the population for an 18-wk period. The susceptibility of the population declined from 100% to about 50% and remained at that level for several months after releases were terminated. Separate experiments showed that the fitness of the adult males and larvae of the refractory strain was much less than that of the susceptible caged strain. The observed change in the susceptibility of the caged population was compared with the expectations on various assumptions about the relative fitness of the refractory and susceptible strains. It appears that initially the efficiency of the replacement process was considerably reduced because of poor fitness of the refractory strain. Once the refractoriness genes were in the caged population, however, they were able to recombine with the genes causing poor fitness and the latter could be eliminated by natural selection, leaving a considerable degree of refractoriness in the population. The results are discussed in relation to the possibility of vector control by the release of males from a refractory strain and with particular reference to the advantages and disadvantages of the use of a negatively heterotic system to assist the replacement process and the release of both sexes.
A theoretical-analysis of the effects of sex-chromosome aneuploidy on X-chromosome and Y-chromosome meiotic drive
4476Lyttle, TW, Evolution, 36:822-831. 1982-01-14 00:00:00.
Extra sex chromosomes are normally detrimental to the individual carrying them. In XY (or WZ) sex determining systems, an extra X chromosome in the homogametic sex generates enough X-autosome imbalance to usually cause inviability, or at least sterility. On the oth- er hand, extra Y chromosomes are some- times tolerated, although in mammals and other higher organisms where the Y is ac- tively involved in sexual development, XXY individuals are generally sterile. In Drosophila and perhaps other inverte- brates where the Y is largely genetically inert, a single extra Y may be permitted in both sexes, while two extra copies is only fertile in XXYY females (Cooper, 1956), if at all.
Control of tsetse flies, Glossina spp.
26683D. A. Dame and A. M. Jordan, Advances in Veterinary Science and Comparative Medicine, 25:101-119. 1981-07-18 13:09:37.
Studies of SIT in Zimbabwe with releases of chemosterilized G. m. morsitans (Dame and Schmidt, 1970) demonstrated the feasibility of the methodology used both in the laboratory and in the field. Subsequent trials were recently completed in Tanzania, where laboratory bred sterile males were released into the natural breeding areas of a population of flies that had been partially suppressed by two aerial applications of endosulfan. Over a quarter of a million irradiated insects were released to control the G. m. morsitans population on a 195-km2 cattle ranch. The flies proved to be fully competitive andeffective. If it had been possible to isolate the plot from immigrating tsetse, the natural population on the ranch would probably have beep eliminated with a substantially lower number of flies than was necV essary to maintain the prolonged 90% level of control that was achieved (Dame et al., 1980). In Upper Volta, similar advances werd made with sterile G. p. gambiensis, bred in the laboratory and released in linear riverine habitats. Glossina p. gambiensis was eradicated from an 11-km section of the experimental plot (Cuisance et al., 1980)/ These accomplishments were completed after extensive study in Chad/ the Central African Republic, and Upper Volta.
Meiotic drive at the D(MD) locus and fertility in the mosquito, Aedes aegypti (L)
4479Youngson, JW, H. M.; Wood, R. J., Genetica, 54:335-340. 1981-01-17 00:00:00.
The Distorter gene D in Aedes aegypti shows meiotic drive when associated with the male determining M gene, causing sex ratio distortion in favour of males. The fertility of Distorter (MD /ms) and normal (M/m-) males has been compared after mating them to a series of 20 females at daily intervals. ; Males of each genotype inseminated up to 13 fe. males (mean 8.0 - 9.0). The major difference was in the significantly greater number of inviable eggs produced by females mated to Distorter males. It is postulated that these eggs were fertilised by abnormal spermatozoa. Females mated to Distorter males also produced significantly greater numbers of shrivelled i.e. unfertilised eggs, indicating a lower density of effective spermatozoa.; The difference in percentage hatch from the two matings was small, indicating that spermatozoa were produced in superabundance so that the overall fertility of Distorter males was not greatly reduced.
A 2-locus model for polymorphism for sex-linked meiotic drive modifiers with possible applications to Aedes aegypti
4478Maffi, GJ, S. D., Theoretical Population Biology, 19:19-36. 1981-01-16 00:00:00.
A two-locus model is presented which shows the possibility of maintaining a polymorphism for modifiers of sex-linked meiotic drive in the absence of fitness differences. The model is very similar to the situation actually found in some laboratory strains of the mosquito Aedes aegypti. The existence of a stable polymorphism usually requires sufficiently loose linkage between the two loci.
Experimental population-genetics of meiotic drive systems .3: Neutralization of sex-ratio distortion in Drosophila through sex-chromosome aneuploidy
4477Lyttle, TW, Genetics, 98:317-334. 1981-01-15 00:00:00.
Laboratory populations of Drosophila melanogaster were challenged by; pseudo-Y drive, which mimics true Y-chromosome meiotic drive through the; incorporation of Segregation Distorter (SD) in a T(Y;2) complex. This causes; extreme sex-ratio distrotion and can ultimately lead to population extinction.; Populations normally respond by the gradual accumulation of drive suppressors,; and this reduction in strength of distortion allows the sex ratio to move; closer to the optimal value of 1:l. One population monitored, however, was; rapidly able to neutralize the effects of sex-ratio distortion by the accumulation; of sex-chromosome aneuploids (XXY, XYY) . This apparently occurs because; XX-bearing eggs, produced in relatively high numbers (-4%) by XXY; genotypes, become the main population source of females under strong Ychromosome; drive. Computer simulation for a discrete generation model incorporating; random mating with differences in fitness and segregation permits; several predictions that can be compared to the data. First, sex-chromosome; aneuploids should rapidly attain equilibrium, while stabilizing the population; at -60% males. This sex ratio should be roughly independent of the strength; of the meiotic drive. Moreover, conditions favoring the accumulation of drive; suppressors (e.g., weak distortion, slow population extinction) are insufficient; for maintaining aneuploidy, while conditions favoring aneuploidy (e.g., strong; distortion, low production of females) lead to population extinction before drive; suppressors can accumulate. Thus, the different mechanisms for neutralizing; sex-ratio distortion are complementary. In addition, Y drive and sex-chromosome; aneuploidy are potentially co-adaptive, since under some conditions; neither will survive alone. Finally, these results suggest the possibility that; genetic variants promoting sex-chromosome nondisjunction may have a selective; advantage in natural populations faced with sex-ratio distortion.
Combining the meiotic drive gene-D and the translocation T-1 in the mosquito, Aedes aegypti(L) .2: Recombination
4481Pearson, AMW, R. J., Genetica, 54:79-85. 1980-01-19 00:00:00.
Recombination on the sex-chromosome of Aedes aegypti has been studied in male genotypes incorporating the sex-linked translocation T1 and the meiotic drive gene D from three different strains (Trinidad, Bozo and Caracas).
Combining the meiotic drive gene-D and the translocation-T1 in the mosquito, Aedes aegypti (L) .1: Sex-ratio distortion and fertility
4480Pearson, AMW, R. J., Genetica, 51:203-210. 1980-01-18 00:00:00.
Sex-ratio distortion has been investigated in males carrying the Y(M)-linked meiotic-drive gene D, from three different strains (Bozo, Caracas and Trinidad), paired with Chipei X-chromosomes highly sensitive to D. The effect of D was tested on its own and also associated with a 1-3 translocation (designated TI). The fertility of males homozygous and heterozygous for the translocation, with and without D, was also investigated
Experimental population-genetics of meiotic drive systems .2: Accumulation of genetic modifiers of Segregation Distorter (SD) in laboratory populations
4482Lyttle, TW, Genetics, 91:339-357. 1979-01-20 00:00:00.
The accumulation of modifiers of the meiotic-drive locus Segregation; Distorter (SD) in Drosophila melanogaster was monitored by measuring the; changes in the mean and variance of drive strength (in terms of “make” value); that occur in laboratory populations when SD and SD+ chromosomes are in; direct competition. The particular SD lines used are T(Y;Z),SD translocations; showing pseudo-Y drive. Four sets of population cages were analyzed. Two sets; were monitored for changes in SD fitness and drive strength (presumed to be; positively correlated) and analyzed for the presence of autosomal dominant; or X-linked modifiers after long periods of time. The remaining two sets were; made up of cages either made isogenic or variable for background genetic; material, and these were used to test whether the rate of accumulation of; modifiers was dependent on initial genetic variability.-Contrary to previous; studies in which most suppression of SD action could apparently be attributed; to a few dominantly acting modifiers of large effect, the conclusion here is; that laboratory populations that are initially free of such major dominant loci; evolve to suppress SD action by accumulating polygenic, recessive modifiers,; each of small effect, and that much of the required genetic variability can be; generated a!e novo by mutation. Possible explanations for these seemingly incompatible results and the evolutionary implications for SD are considered.
Sex-ratio trait in Drosophila pseudoobscura – Fertility relations of males and meiotic drive.
4483Beckenbach, AT, American Naturalist, 112:97-117. 1978-01-21 00:00:00.
In the early analysis of the "sex-ratio" polymorphism (SR) of Drosophila pseudoobscura, complete meiotic drive was assumed, and study centered on the nature of the selective forces opposing its spread. Policansky and Ellison (1970) found that the mechanism of SR involved the degeneration of half the spermatids during spermatogenesis. They suggested that little or no drive may be expressed due to a fertility deficiency of SR males. Thus little or no selection is required to balance the drive. I report studies conducted to determine the conditions under which either of these alternatives might hold. Virgin females were mated once to either SR or ST (standard) males aged as virgins for 3 days, and their fecundities were determined by daily egg counts. No differences were found between the two groups in either daily egg production or egg-to-adult survival of the progenies. Only females maintained with males throughout the experiment were clearly superior in these parameters. No fertility differences between SR and ST males are unconditional. Fertilities of males aged for varying lengths of time as virgins were determined by mating them to as many virgin females as they would inseminate in a brief span of time. Time periods ranged from 3 to 8 h, depending on the ages of the males. Fertility of the SR males was lower than that of ST males of the same age for males aged 20-33 h from eclosion. Differences in 4-day-old males were not so clear. When 4-day-old males which had depleted their stores of sperm by repeated matings were retested after 12 h of rest, SR males again showed lower fertility than ST males. The fertility reduction of SR males occurs only during the first few days as adults or after repeated matings. The effect of different degrees of insemination on the pattern of production of fertile eggs was examined by mating virgin females to males which were either virgin (heavy insemination) or with seminal vesicles partially depleted by three previous matings (light insemination). No differences in either fecundity or hatchability between the groups were observed early in the reproductive period, but the hatchability of the eggs produced by the lightly inseminated females declined sooner than that of the heavily inseminated group. This response would minimize the populational consequences of fertility differences in males unless the females remate. It is suggested that the conditional fertility differences between SR and ST males are of little consequence until the females remate. Depending on the time of remating, there is potentially a wide range in the amount of meiotic drive expressed.
Transporting marker gene re (red eye) into a laboratory cage population of Aedes aegypti (Diptera Culicidae), using meiotic drive at MD locus
4486Wood, RJC, L. M.; Hamilton, A.; Whitelaw, A., Journal of Medical Entomology, 14:461-464. 1978-01-04 00:00:00.
An attempt has.been made to use the meiotic drive gene MD to transport a marker re (red eye) into a laboaratory population of the mosquito Aedes aegypti. The experiment produced an increase in re frequency, but also indicated that this gene has unexpectedly high fitness in the laboratory. The need for field estimates of fitness is indicated.
Sex ratio distortion caused by meiotic drive in a mosquito Culex pipiens
4485Sweeny, TLB, A. R., Genetics, 88:427-446. 1978-01-03 00:00:00.
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.
Transporting marker gene re (red eye) into a laboratory cage population of Aedes-aegypti (Diptera Culicidae), using meiotic drive at MD locus
6233R. J. Wood, L. M. Cook, A. Hamilton and A. Whitelaw, Journal of Medical Entomology, 14:461-464. 1977-12-24 21:51:08.
An attempt has been made to use the meiotic drive gene MD to transport a marker re (redeye) into a laboratory population of the mosquito Aedes aegypti. The experiment produced an increase in re frequency, but also indicated that this gene has unexpectedly high fitness in the laboratory. The need for field estimates of fitness is indicated.
Sterility introduced by release of genetically altered males to a domestic population of Aedes aegypti at the Kenya coast
25875P. T. McDonald, W. Hausermann and N. Lorimer, Am J Trop Med Hyg, 26:553-61. 1977-05-06 07:09:31.
The release of males heterozygous for one or two sex-linked translocations was effective in introducing a high level of sterility into a domestic population of Aedes aegypti at a Rabai village. The effect of the releases continued for several weeks after the release period. Male mosquitoes, Aedes aegypti, were released at the Kenya coast to test the effectiveness of laboratory engineered mosquitoes in introducing a genetic mechanism and the ability of the mechanism to establish itself under field conditions. A triplicate of Rabai villages was selected for the experiment. In the 1st village nottreatment was made. In the 2nd village the domestic water containers were cleaned twice a week to remove larvae and pupae. Translocation males were released in the 3rd village. A mixture of 2 types of males was introduced: the single heteroxygote male selected from 78 translocations induced by irradiation in the African strains, and the double heterozygote male. Genetic analysis of the content of release samples determined quality control of released males. Fertility was also determined with females of a strain collected at Chibarani before releases began. Hatchability of eggs in all villages was counted to assay sterility in all villages. Before the releases population fluctuations in the 3 villages were monitored for 20 weeks. The release mixture had a fertility of 37% and the single heterozygote of 50%. A daily survival rate of .63 was shown for the dusted release males. There was close agreement between the monitoring for sterility for both the egg collections and the oviposition of the LB catch females. The sterility introduced into the Chibarani population was extensive.
Resistance to meiotic drive at MD locus in an Indian wild population of Aedes aegypti
4488Suguna, SGW, R. J.; Curtis, C. F.; Whitelaw, A.; Kazmi, S. J., Genetical Research, 29:123-132. 1977-01-06 00:00:00.
Females from an Indian wild population of Aedes aegypti were crossed to males carrying the sex ratio distorter factor MB which shows meiotic drive. Progenies from ¥1 males were tested for sex ratio distortion, i.e. the chromosomes from the wild females were screened for their resistance to the action of M°. The distribution of sex ratio in the progenies of different ¥1 males indicated a polymorphism in the wild population for resistant and sensitive variants of the X chromosome. Seven discrete categories of X appear to exist, associated with sex ratios ranging from 50 % $ to less than 1'25 % $. The overall level of resistance varied slightly but significantly in different parts of a town. The results are discussed in relation to the use of sex ratio distortion for genetic control of mosquitoes.
Experimental population-genetics of meiotic drive systems .1: Pseudo-Y chromosomal drive as a means of eliminating cage populations of Drosophila melanogaster
4487Lyttle, TW, Genetics, 86:413-445. 1977-01-05 00:00:00.
The experimental population genetics of Y-chromosome drive in Drosophila; melanogasier is approximated by studying the behavior of T(Y;S),SD lines.; These exhibit “pseudo-Y” drive through the effective coupling of the Y chromosome; to the second chromosome meiotic drive locus, Segregation distorter; (SD). T(Y;S),SD males consequently produce only male offspring. When; such lines are allowed to compete against structurally normal SD+ flies in; population cages, T(Y;S),SD males increase in frequency according to the; dynamics of a simple haploid selection model until the cage population is; eliminated as a result of a deficiency in the number of adult females. Cage; population extinction generally occurs within about seven generatiomSeveral; conclusions can be drawn from these competition cage studies:; (1) Fitness estimates for the T(Y;Z),SD lines (relative to SD+) are generally; in the range of 2-4, and these values are corroborated by; independent estimates derived from studies of migration-selection; equilibrium.; (2) Fitness estimates are unaffected by cage replication, sample time, or; the starting frequency of T(Y;Z),SD males, indicating that data from; diverse cages can be legitimately pooled to give an overall fitness; estimate.; (3) Partitioning of the T(Y;S),SD fitnesses into components of viability,; fertility, and frequency of alternate segregation (Y + SD from; X+SD+) suggests that most of the T(Y;S),SD advantage derives; from the latter two components. Improvements in the system might; involve increasing both the viability and the alternate segregation to; increase the total fitness.; While pseudo-Y drive operates quite effectively against laboratory stocks,; it is less successful in eliminating wild-type populations which are already; segregating for suppressors of SD action. This observation suggests that further
Field trial of competitive displacement of Aedes-polynesiensis by Aedes-albopictus on a Pacific atoll
6235L. Rosen, L. E. Rozeboom, W. C. Reeves, J. Saugrain and D. J. Gubler, American Journal of Tropical Medicine and Hygiene, 25:906-913. 1976-11-01 21:53:54.
Prior laboratory studies and field observations suggested that it might be possible to reduce the size of the population of, or eliminate, Aedes polynesiensis by the introduction of Aedes albopictus. The former mosquito is the principal vector of nonperiodic filariasis caused by Wuchereria bancrofti and the latter is a closely related species refractory to the development of human filariae. The practicability of such competitive displacement was studied by a field trial on a remote coral atoll where there was an established population of A. polynesiensis. Three strains of A. albopictus were liberated at separate localities on the atoll and their fate was followed for 4 years. One strain disappeared within 12 months after release and the other two disappeared within 48 months. It was not clear whether A. albopictus failed to become established because the strains were unsuitable, the general environment was inappropriate, or A. polynesiensis was present in such numbers that A. albopictus rarely succeeded in mating with its own species.
Between family variation in sex-ratio in Trinidad (T-30) strain of Aedes-aegypti (L) indicating differences in sensitivity to meiotic drive gene MD
4494Wood, RJ, Genetica, 46:345-361. 1976-01-12 00:00:00.
Sex ratio in the Trinidad (T-30) strain of Aedes aegypti has remained constant at around 43%? during seventeen years of laboratory culture. The divergence from 50% is due to meiotic drive by the MD gene on the Y chromosome. The driving Y chromosome gives a much more distorted sex ratio (mean = 5.7%?) when coupled with the highly sensitive X chromosomes from strain 64. This was demonstrated in all of 98 families tested, indicating that all or most of the Y chromosomes in T-30 carry the MD gene. Consequently the low level of sex ratio distortion in T-30 must be due to resistance to MD.; ; Crosses made within T-30 demonstrated wide differences in sex ratio between families, depending on the sensitivity of the male parent's X chromosome to MD. However, sex ratios were not continuously variable but fell within fairly discrete categories. Thus, X chromosomes could be classified according to the modal sex ratios associated with them: ms3 (12.5%?), ms2 (32.5%?), ms1 (40%?), mr1 (47.5%?) mr2 (57.5%?).; ; The different sex ratio categories were more discrete in the families of sib matings than from random matings, suggesting the possibility of background modification of what is essentially a balanced polymorphism. Evidence is presented suggesting that the polymorphism could be due to interaction at two loci. A further X variant, ms4 (<10%?) characterised strain 64 but was absent from T-30.; ; A comparison of fertility between the different sex ratio categories in T-30 established that sex ratio distortion was not caused by differential mortality after fertilisation.
Population genetics of modifiers of meiotic drive.3. Equilibrium analysis of a gneral model for genetic control of segregation distortion
4493Thomson, GJF, M. W., Theoretical Population Biology, 10:8-25. 1976-01-11 00:00:00.
Prout, Bungaard and Bryant (1973, Theor. Popul. Biol. 4, 446–465) presented the first formal treatment of a model of meiotic drive involving a modifier locus which controls the intensity of drive. They studied the equilibrium behavior in the simplest model where it is assumed that drive is maximal when not suppressed. In that case there is one polymorphic equilibrium at which there is linkage disequilibrium. The equilibrium solutions in the general model of meiotic drive proposed by Prout, et al. are given in this paper together with a stability analysis. It is shown that up to three polymorphic equilibria may exist, two of which are in linkage disequilibrium and one in linkage equilibrium. These equilibria exhibit behavior qualitatively opposite to what is widely accepted as the usual for two locus systems and which is not seem in the simple case originally treated. The polymorphic equilibria with linkage disequilibrium may be stable for loose linkage and not for tight while that with linkage equilibrium is stable in an interval of relatively tight linkage values.
Evidence for autosomal meiotic drive in the butterfly Danaus chrysippus L.
4492Smith, DAS, Heredity, 36:139-142. 1976-01-10 00:00:00.
Danaus chrysippus (Danaidae) in East Africa is highly polymorphic for colour, the genetic control of which resides at three loci. The B locus has two alleles, B giving a nutbrown ground colour and bb orange on both fore and hindwings. The C locus determines forewing pattern: there are two alleles, C giving a wing uniformly coloured except for a black margin (form dorippus) and cc a large black apical area traversed by a row of white subapical spots (form ae&yptius = form chrysippus of my earlier papers). Heterozygotes (Cc) are basically dorippus but are often phenotypically distinct in showing the "aegyptius" subapical spots on the underside of the forewing. The B and C loci are closely linked (Smith, 1975a). The A locus has a recessive allele a the homozygous possessor of which has a large white patch on the hindwing (form alcippus when combined with the aegyptius forewing and form albinus with the dorippus forewing). The A locus probably assorts independently from the B and C loci (Clarke, Sheppard and Smith, 1973; Smith, 1975a). All-female broods commonly occur in D. chrysippus. These probably result when a Y-linked gene D causes meiotic drive for the Y chromosome so that it always enters the secondary oocyte at the first meiotic division in the female. Females from all-female broods usually themselves produce allfemale broods but a switch to bisexual broods can occur and seems to depend on the acquisition of a dominant autosomal suppressor gene S from the maternal male grandparent. The S locus is probably closely linked with the C locus (Smith, 1975b).
Cytogenetic analysis of meiotic drive in mosquito, Aedes aegypti
4491Newton, MEW, R. J.; Southern, D. I., Genetica, 46:297-318. 1976-01-09 00:00:00.
Meiotic drive in Aedes aegypti (L.) is shown by a Giemsa C-banding technique to be associated with. preferential isochromatid breakage of the X chromosome during male meiosis. These breaks remain open at least until anaphase-I and, since the range of cells affected is proportional to the sensitivity of the X chromosome to the Distorter gene, it is argued that they are directly related to the decreased number of spermatozoa found in distorting males. This reduction is considered to be attributable to the degeneration of more X- than Y-bearing spermatids but it is probable that some non-functional X-bearing spermatozoa are also produced. Chromosome breakage is almost completely confined to four sites, two adjacent to the centromere, one just proximal to the intercalary band and another about the centre of the unbanded arm. Although the first three of these lie within a region in which crossing-over does not take place, fragmentation occurs more frequently in a chiasmate arm than in one devoid of chromatid exchange.
Population replacement in Culex-fatigans by means of cytoplasmic incompatibility .2. Field cage experiments with overlapping generations
6276C. F. Curtis, Bulletin of the World Health Organization, 53:107-119. 1976-01-08 16:51:11.
Three experiments were carried out in field cages to test the principle of " transport" of a desirable gene or chromosome into a wild Culex fatigans population as a result of the sterility in cross-matings associated with cytoplasmic incompatibility. Cycling populations of Delhi origin were established in the cages and daily releases were made of the IS31B strain, which has Paris cytoplasm and carries a male-linked translocation. It was shown that, if sufficient releases were made to establish a majority of the Paris cytoplasmic type, complete replacement by this cytoplasmic type subsequently occurred. However, as a result of partial compatibility of males of the Delhi population with Paris females, " recombinant " males with Paris cytoplasm and no translocation were produced. In an experiment in which a continuous low rate of " immigration " of a strain of Delhi origin was simulated, a gradual increase of the Paris cytoplasm non-translocated type occurred, and renewed IS31B releases were necessary after 5 months to restore the predominance of this type. The results are compared with computer predictions and discussed in relation to the transport of genes for filaria refractoriness or chromosome translocations into wild populations.
Modifier theory of meiotic drive: Is Mendelial segregation stable
4490Liberman, U, Theoretical Population Biology, 10:127-132. 1976-01-08 00:00:00.
The evolutionary fate of rare modifiers, based on the modifier theory of meiotic drive, is studied in this paper. It is shown that a polymorphism based on Mendelian segregation is never stable for any recombination frequencies between 0 and 12, and that, for tight linkage between the main locus and the modifier locus, the modifier locus tends towards heterozygosity.
Meiotic drive for B-chromosomes in primary oocytes of Myrmeleotettix maculatus (Orthoptera-Acrididae)
4489Hewitt, GM, Chromosoma, 56:381-391. 1976-01-07 00:00:00.
Using a modified technique which allowed observation of chromosome orientation in the primary oocyte of grasshoppers at the onset of anaphase, it has been possible to establish that the B-chromosome is distributed preferentially on the egg side of the metaphase plate rather than the polar body side. The frequency of this preferential orientation matches very closely the level of preferential transmission determined from breeding experiments using individuals from the same population. The spindle is asymmetrical in the primary oocyte of this species, and a possible explanation of the meiotic drive is proposed as a result of the conical shape of nucleoplasm surrounding this spindle. The autosomal chiasma frequency of these females is generally lower than comparable males and is increased by the presence of B chromosomes; but the chiasma frequencies of the sexes respond differently to the addition of 1 and 2 B-chromosomes.
Population genetics of modifiers of meiotic drive 4: Evolution of sex-ratio distortion
4497Thomson, GJF, M. W., Theoretical Population Biology, 8:202-211. 1975-01-15 00:00:00.
A model for the evolution of the sex-ratio meiotic drive system in Drosophila is proposed and analyzed. The model incorporates drive and altered fertility genetic modification The condition change in the sex-ratio of the modifying distortion overcome any relative of meiotic in the carriers of the modified sex-ratio chromosomes. that a sex-ratio modifying chromosome increase is that the relative fertility chromosome. When no fertility model predicts that any increase in distortion differences are involved, of the sex ratio will be favored. loss in carriers the
Sex-chromosome meiotic drive systems in Drosophila melanogaster .1: Abnormal spermatid development in males with a heterochromatin-deficient X-chromosome (sc4sc8)
4496Peacock, WJM, G. L. G.; Goodchild, D. J., Genetics, 79:613-634. 1975-01-14 00:00:00.
The meiotic drive characteristics of the In(1)sc4Lsc8R/Y system have been examined by genetic analysis and by light and electron microscopy. sc4sc8/Y males show a direct correlation between nondisjunction frequency and meiotic drive. Temperature-shift experiments reveal that the temperature-sensitive period for nondisjunction is at meiosis, whereas that for meiotic drive has both meiotic and post-meiotic components. Cytological analyses in the light and electron microscopes reveal failures in spermiogenesis in the testes of sc4sc8 males. The extent of abnormal spermatid development increases as nondisjunction becomes more extreme.
Modifier theory of meiotic drive
4495Hartl, DL, Theoretical Population Biology, 7:168-174. 1975-01-13 00:00:00.
The evolutionary fate of rare modifiers of recessive lethal segregation distorters has been studied. Suppressors or partial suppressors will always increase in frequency. Enhancers will increase in frequency if linkage is sufficiently tight and be lost if linkage is sufficiently loose.
Sex-ration, meiotic drive, and group selectin in Drosophila pseudoobscura
4498Policansky, D, American Naturalist, 108:75-90. 1974-01-16 00:00:00.
Sex ratio (SR) is a widespread genetic condition of the X-chromosome in Drosophila species which causes males to produce progenies consisting almost entirely of females. Results of samples from natural populations of Drosophila pseudoobscura and results of some laboratory experiments indicate that SR males produce only about half as many sperm as normal (ST) males; because of this deficiency, SR males are able to fertilize only about half as many eggs as ST males. These results explain the observed equilibria of frequencies of SR in natural populations, and suggest that, at least in the case of D. pseudoobscura, male fertility may be partly limited by the number of sperm males can produce.
Population replacement in Culex fatigens by means of cytoplasmic incompatibility. Laboratory experiments with non-overlapping generations
6291C. F. Curtis and T. Adak, Bulletin of the World Health Organization, 51:249-255. 1974-01-08 19:45:42.
Bidirectional cytoplasmic incompatibility in the Culex pipiens complex appears to provide a mechanism for the replacement of a wild population by a strain refractory to filaria or a strain made partly sterile by a translocation. As a preliminary test of the feasibility of the replacement process, various ratios of strains with the cytoplasm of either Delhi or Paris, which are bidirectionally incompatible, were tested in laboratory cages. Where one strain was marked with the ruby-eye gene, this strain always declined in frequency in the next generation. In experiments in which the Paris strain was marked with a male-linked translocation complex, after 2-4 generations of breeding there was complete elimination of either the Paris or the Delhi type depending, as expected, on the relative frequencies of the two types with which the population began. In one experiment a type with Paris cytoplasm devoid of the translocation was found. This type increased in frequency in succeeding generations. The possible causes of origin of this type and its relevance to the practical use of the replacement principle are discussed.
Genetic control of insect populations: I. Cage studies of chromosome replacement by compound autosomes in Drosophila melanogaste
6297M. Fitz-Earle, D. G. Holm and D. T. Suzuki, Genetics, 74:461-475. 1973-07-08 19:53:27.
A genetic method for insect control was evaluated using the test organism, Drosophila melanogaster. The technique involved the displacement under a system of continuous reproduction, of standard strains by those carrying compound autosomes. The eradication of the replacements could subsequently be achieved through the use of temperature-sensitive lethal mutations.—While certain compound autosome strains failed to displace standards in population cages, even at the initial release ratio of 25:1, others were highly successful. Indeed, for some strains when the ratio of compounds to standards was as low as 9:1, the population rapidly went to fixation in favor of the compound line.—Hatchability was found to be an insufficient index of fitness to estimate the initial ratios of compounds to standards that would guarantee fixation of the former. Differences in other fitness components, such as development time, were detected that could seriously modify displacement, especially with continuous overlapping generations. The importance of examining the fitness of various compound lines and selecting the most competitive in cages, prior to field tests, cannot be overemphasized.
Lâchers de mâles stériles de Glossina tachinoides West. dans un gîte naturel de faible densité Bas-Logone, Cameroun
26657D. Cuisance and J. Itard, Revue d’élevage et de médecine vétérinaire des pays tropicaux, 26:405-422. 1973-04-01 06:33:32.
Des mâles adultes de G. tachinoides, élevés à Maisons-Alfort et irradiés entre 7 600 et 10 650 rads à Saclay (France), ont été expédiés chaque semaine par avion à N'Djamena (Tchad) entre février et juin 1973, pour être, après marquage, lâchés en plusieurs points d'un gîte naturel, sur les berges du Logone. Par suite d'une sécheresse exceptionnelle, la population de mouches sauvages dans ce gîte étant de faible densité, la proportion de mâles stériles lâchés a pu être élevée, le rapport mâles stériles/mâles sauvages étant, en moyenne, pendant toute la période des lâchers, de 2,8/I. La longévité moyenne des mâles stériles a été de 6,5 jours contre 8 jours pour les mâles sauvages. Les mâles stériles ont eu un comportement identique à celui des mâles sauvages. Bien qu'un autre gîte, qui servait de témoin, ait été fortement dégradé par l'homme et les animaux, ce qui n'a pas permis d'apprécier exactement l'effet des lâchers de mâles stériles dans le gîte d'expérience, on estime cependant qu'à partir de la mi-mars, la chute de densité de la population sauvage est en grande partie due à la présence des mâles stériles, ce qui semble confirmé par l'observation de femelles sauvages capturées dans les deux gîtes: 69 p. 100 des femelles capturées dans le gîte d'expérience n'ont eu aucune descendance au cours de trois semaines d'observation, alors que toutes les femelles du gîte témoin ont produit une pupe dans les huit jours suivant leur capture
Comportement de mâles stériles de Glossina tachinoides West. lâchés dans les conditions naturelles – environs de Fort-Lamy (Tchad). I. Transport, lâchers, rythme d’activité, action sur la population sauvage
26645D. Cuisance and J. Itard, Revue d'élevage et de médecine vétérinaire des pays tropicaux, 26:55-76. 1973-01-01 15:42:14.
Glossina tachinoides adult males, bred and irradiated with 15,500 rads in Maisons-Alfort (France) were dispatched by air-mail to Fort-Lamy (Chad) between February and May of 1972, in order to be released, after marking, in a natural area of Cameroon side of the Chari river. In this first part, the authors analyse the consequences of breeding-irradiation-transport-handling ” factors on sterile males behaviour and activity rhythm. The too small a quantity of sterile males is essentially the cause of the absence of any measurable effect on naturel population evolution.
Changing population structure through the use of compound chromosomes
6295D. Childress, Genetics, 72:183-186. 1972-09-08 19:50:49.
Theoretical calculations and population cage data are presented to illustrate the use of compound chromosomes to change the genetic structure of insect populations.
Chromosome rearrangements for the control of insect pests
6293G. G. Foster, M. J. Whitten, T. Prout and R. Gill, Science, 176:875-880. 1972-05-26 19:48:27.
Over several years some biologists have been interested in the possibilities of employing genetic techniques in the control of insect pests. One idea has been to introduce in the natural population genotypes which could subsequently facilitate control, or which might render the pest innocuous. An- other idea that followed from the success of the .'sterile male" technique was to release genotypes with chromosomal aberrations whose subsequent segregation would result in sterility effects damaging to the population. Whitten (I) suggested combining these two ideas in one operation: in its simplest form the desired genotype would be obtained by incorporating the required genes in a chromosomal translocation. This would then be released as a homozygote in excess of the intrinsic unstable equilibrium which would result from the semisterility of the translocation heterozygote. The translocation producing the desired genotype would then autonomously become fixed while the genotype at the same time would produce sterile progeny in the early stages of the process. Thus we have the concept of a genetic transporting mechanism and a desired genotype to be transported, with the additional benefit of a transport device that might itself have transient damaging effects.
Multiple meiotic drive systems in Drosophila melanogaster male
4499Miklos, GLGY, A. F.; Peacock, W. J., Genetics, 72:105-115. 1972-01-17 00:00:00.
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.
