| the population genetics of parthenogenetic strains of drosophila mercatorium. ii the capacity for parthenogenesis in a natural, bisexual population. | drosophila mercatorum is a bisexual species, but certain strains are capable of parthenogenetic reproduction in the laboratory. we investigated the parthenogenetic capacity of the virgin daughters of females captured from a natural, bisexual population in hawaii. an isozyme survey indicated the natural population is polymorphic at about 50% of its loci, and its individuals heterozygous at 18% of their loci. the predominant mode of parthogenesis in d. mercatorum causes homozygosity for all loci i ... | 1976 | 1269907 |
| differences in life history traits between alcohol dehydrogenase genotypes of drosophila mercatorum: background and maternal genotype effects. | the effects of genotype at the alcohol dehydrogenase (adh) locus on developmental time and fecundity were studied using three strains of drosophila mercatorum. all three strains had similar genetic backgrounds and two were homozygous for the same electrophoretic allele (f for fast). the third strain was homozygous for the slow allele (s). the life history traits of all possible progeny of these strains were studied. the results showed that for both mean developmental time and pattern of eclosion ... | 2012 | 3506533 |
| the molecular through ecological genetics of abnormal abdomen in drosophila mercatorum. vi. the non-neutrality of the y chromosome rdna polymorphism. | an association between quantitative variation of rdna on the y chromosome and male expression of the juvenilized, adult cuticle of the abnormal abdomen syndrome has been found for drosophila mercatorum. many pleiotropic effects of this syndrome have been described previously for females, but little was known about possible pleiotropic effects in males. the effects on males open up new avenues for the action of natural selection operating on the system. in females, the syndrome causes an increase ... | 1994 | 8013914 |
| structure and ultrastructure of spermatozoon in six species of drosophilidae (diptera). | the drosophilidae family is formed by brachycera diptera distributed widely across different regions of the planet. it is composed of about 4000 species, 304 of which are found in brazil. the objective of this work was to characterize morphologically the structure of the male internal reproductive apparatus and the ultrastructure of the spermatozoon in four neotropical (drosophila cardini, d. mercatorum, d. nebulosa and d. sturtevanti) and two invasive (d. simulans and zaprionus indianus) specie ... | 2016 | 28029387 |
| wing shape heritability and morphological divergence of the sibling species drosophila mercatorum and drosophila paranaensis. | the fruit-flies drosophila paranaensis and drosophila mercatorum pararepleta are sibling species belonging to the repleta group. females of these two species are normally considered to be morphologically indistinguishable while males only differ consistently in the morphology of their genitalia. these species are sympatric throughout a large area of their geographic distribution. in this study, we investigated the degree of morphological divergence between d. paranaensis and d. mercatorum parare ... | 2004 | 15107807 |
| coadapted gene complexes for morphological traits in drosophila mercatorum. two-loci interactions. | the availability of molecular and morphological markers in a parthenogenetically reproducing strain of drosophila mercatorum allowed us to design an experiment in which we could obtain a sample of completely homozygous recombinant females from two different parental homozygous strains. the phenotypic values of body-size-related measures and bristle numbers (sternopleural and abdominal) were measured in females sampled from the parental, f1 and f2 generations. the dna extracted from the f2 flies ... | 1999 | 10447703 |
| natural selection and ribosomal dna in drosophila. | natural populations of drosophila mercatorum are variable for the number of x-linked 28s ribosomal genes bearing a 5-kilobase insert. a separate polymorphic x-linked gene controls whether 28s repeats bearing the insert are preferentially underreplicated during the formation of polytene tissue. female flies having at least a third of their 28s genes bearing the insert and lacking the ability to preferentially underreplicate inserted repeats display the abnormal abdomen syndrome. the syndrome is c ... | 1989 | 2556326 |
| the parthenogenetic capacities and genetic structures of sympatric populations of drosophila mercatorum and drosophila hydei. | drosophila mercatorum is a sexual species that can reproduce parthenogenetically in the laboratory. a previous study showed that a natural population of d. mercatorum inhabiting the kamuela garbage dump on the island of hawaii could produce both viable parthenogenetic adults and self-sustaining parthenogenetic lines. the present study deals with a second screen for parthenogenesis and an isozyme survey performed on natural populations of d. mercatorum and d. hydei caught in patches of opuntia tu ... | 1979 | 17248952 |
| parents without partners: drosophila as a model for understanding the mechanisms and evolution of parthenogenesis. | of 40 drosophila species screened to date, a majority have shown some ability to at least initiate parthenogenetic development. in one case, drosophila mangebeirai, natural populations are entirely female, making it the only obligate parthenogenetic species of drosophila only a few of the species that exhibit the ability to undergo early embryonic development of unfertilized eggs successfully respond to selection for parthenogenetic production of adult flies. laboratory strains of parthenogeneti ... | 2013 | 23550124 |
| cytological investigation of the mechanism of parthenogenesis in drosophila mercatorum. | thelytokous parthenogenesis (female progeny only) in animals is believed to arise initially in unfertilized eggs produced by bisexual females via the fusion of two haploid nuclei following meiosis, to produce diploid female progeny. the transition from sexual to parthenogenetic mechanisms of reproduction requires that the egg replace the paternal contributions of a haploid genetic complement and the basal body, which is thought to be essential for centrosome formation. the transitional facultati ... | 2009 | 18820446 |
| drosophila parthenogenesis: a tool to decipher centrosomal vs acentrosomal spindle assembly pathways. | development of unfertilized eggs in the parthenogenetic strain k23-o-im of drosophila mercatorum requires the stochastic interactions of self-assembled centrosomes with the female chromatin. in a portion of the unfertilized eggs that do not assemble centrosomes, microtubules organize a bipolar anastral mitotic spindle around the chromatin like the one formed during the first female meiosis, suggesting that similar pathways may be operative. in the cytoplasm of eggs in which centrosomes do form, ... | 2008 | 18313666 |
| the effect of maternal and grandmaternal age in benign and high temperature environments. | maternal age is known to be of importance for the fitness of the offspring. few studies have, however, been able to analyse this phenomenon as an isolated effect without confounding effects through genetic variation. this difficulty can be circumvented by working with parthenogenetic organisms. we investigated the effect of maternal and grandmaternal age on wing traits, pupal survival and developmental instability (di) in both a benign and a high temperature environment using two different parth ... | 2005 | 16188416 |
| heat stress and age induced maternal effects on wing size and shape in parthenogenetic drosophila mercatorum. | maternal effects on progeny wing size and shape in a homozygous parthenogenetic strain of drosophila mercatorum were investigated. the impact of external maternal factors (heat stress) and the impact of internal maternal factors (different maternal and grand maternal age) were studied. the offspring developed under identical environmental conditions, and due to lack of genetic variation any phenotypic difference among offspring could be ascribed to maternal effects. wing size was estimated by ce ... | 2005 | 16033560 |
| maternal and grandmaternal age effects on developmental instability and wing size in parthenogenetic drosophila mercatorum. | age is known to have a large effect upon fertility and survival. here we study the impact of maternal and grandmaternal age on wing size and developmental instability (di) in offspring using a parthenogenetic strain of drosophila mercatorum. this enabled us to cancel out any genetic variance between individuals. the mean centroid size of the wings was estimated in offspring from four maternal/grandmaternal age groups. further, di was calculated by measuring phenotypic variability and correcting ... | 2005 | 15834664 |
| drosophila parthenogenesis: a model for de novo centrosome assembly. | the drosophila egg contains all the components required to properly execute the early mitotic divisions but is unable to assemble a functional centrosome without a sperm-provided basal body. we show that 65% of unfertilized eggs obtained from a laboratory strain of drosophila mercatorum can spontaneously assemble a number of cytoplasmic asters after activation, most of them duplicating in a cell cycle-dependent manner. such asters are formed by a polarized array of microtubules that have their a ... | 2003 | 12921733 |
| evolutionary implications of developmental instability in parthenogenetic drosophila mercatorum. ii. comparison of two strains with identical genotypes, but different modes of reproduction. | developmental instability is particularly pronounced in parthenogenetic strains of drosophila mercatorum. all parthenogenetically produced eggs in a given strain have the same genotype, but even when reared in the same environment, only approximately 5% of the eggs initiating development ever reach adulthood. a sexual analogue of a parthenogenetic strain was created to investigate the basis of this developmental instability. the two strains have identical genotypes (except for the y chromosome i ... | 2006 | 12054296 |
| evolutionary implications of developmental instability in parthenogenetic drosophila mercatorum. i. comparison of several strains with different genotypes. | natural populations of sexually reproducing drosophila mercatorum are capable of a very low rate of parthenogenesis, but this mode of reproduction has apparently never characterized an entirely asexual population in this species. the high abortion rate observed in laboratory parthenogenetic lines suggests that developmental constraints may cause the failure of this trait to spread in nature. to investigate the basis of this developmental instability and how it may affect the evolution of parthen ... | 2006 | 12054295 |
| life-history changes that accompany the transition from sexual to parthenogenetic reproduction in drosophila mercatorum. | in spite of the predicted genetic and ecological costs of sex, most natural populations maintain sexual reproduction, even those capable of facultative parthenogenesis. unfertilized eggs from natural populations of drosophila mercatorum occasionally develop into viable adults, but obligately parthenogenetic populations are unknown in this species. to evaluate the microevolutionary forces that both favor and constrain the evolution of parthenogenesis in d. mercatorum, we have measured parthenogen ... | 2001 | 11392393 |
| retrotransposable elements r1 and r2 in the rdna units of drosophila mercatorum: abnormal abdomen revisited. | r1 and r2 retrotransposable elements are stable components of the 28s rrna genes of arthropods. while each retrotransposition event leads to incremental losses of rdna unit expression, little is known about the selective consequences of these elements on the host genome. previous reports suggested that in the abnormal abdomen (aa) phenotype of drosophila mercatorum, high levels of rdna insertions (r1) in conjunction with the under-replication locus (ur), enable the utilization of different ecolo ... | 1999 | 9927458 |
| experimental evidence for the genetic-transilience model of speciation. | | 1996 | 28568937 |
| obtaining genetic markers by using double-stringency pcr with microsatellites and arbitrary primers. | a technique to obtain genetic markers is described. pcr is performed at two different annealing temperatures in a single reaction mixture. during the first cycles, a single microsatellite oligonucleotide is used as primer to amplify dna between two microsatellite regions. the annealing temperature and consequent stringency is then lowered, and in further cycles a random-amplified polymorphic dna (rapd) primer exponentially amplifies parts of the previously amplified fragments, which contain sequ ... | 1995 | 8588912 |
| the molecular through ecological genetics of abnormal abdomen in drosophila mercatorum. v. female phenotypic expression on natural genetic backgrounds and in natural environments. | the abnormal abdomen (aa) syndrome in drosophila mercatorum depends on the presence of r1 inserts in a third or more of the x-linked 28s rdna genes and the absence of selective underreplication of inserted repeats in polytene tissues that is controlled by an x-linked locus (ur) half a map unit from the rdna complex. this syndrome affects both life history and morphology in the laboratory. because abnormal morphologies are rarely encountered in nature, the purpose of this study is to see if the f ... | 1993 | 8325484 |
| the molecular through ecological genetics of abnormal abdomen. iv. components of genetic variation in a natural population of drosophila mercatorum. | natural populations of drosophila mercatorum are polymorphic for a phenotypic syndrome known as abnormal abdomen (aa). this syndrome is characterized by a slow-down in egg-to-adult developmental time, retention of juvenile abdominal cuticle in the adult, increased early female fecundity, and decreased adult longevity. previous studies revealed that the expression of this syndrome in females is controlled by two closely linked x chromosomal elements: the occurrence of an r1 insert in a third or m ... | 1992 | 1311698 |
| sexual behavior in laboratory strains of drosophila mercatorum that have spontaneously adopted parthenogenesis. | three instances are described in which bisexual laboratory strains spontaneously adopted an exclusively parthenogenetic mode of reproduction, even in the presence of fertile, bisexual males. the few males produced by the parthenogenetic strains lack a y chromosome and are sterile but, nevertheless, showed no correlated impairment of normal mating behavior. in contrast, females show a strong reluctance to accept copulation. this behavioral correlate of parthenogenesis also has been observed previ ... | 1991 | 1863262 |
| asymmetrical mating patterns between geographic strains of drosophila mercatorum: a test of the kaneshiro hypothesis. | | 1991 | 28567882 |
| intraspecific dna divergence in drosophila: a study on parthenogenetic d. mercatorum. | drosophila mercatorum is a species that can give rise to totally homozygous parthenogenetic strains. using the technique of dna-dna hybridization, we have assessed the overall single-copy dna differences among three independently derived strains that represent three independent genomes. among strains, the average difference between homoduplex and heteroduplex median melting temperatures is 1.3 degrees c. this represents greater than or equal to 1.3% base-pair mismatch. normalized percent of reas ... | 1987 | 3447012 |
| temporal and spatial heterogeneity of mtdna polymorphisms in natural populations of drosophila mercatorum. | restriction endonuclease analysis of mtdna was used to examine the genetic relatedness of several geographically separated isolines of the drosophila mercatorum subgroup. in addition, we examined the temporal and spatial distribution of two mtdna restriction site polymorphisms produced by the enzymes bsteii and bstni at a single locality--kamuela, hawaii. due to small sample sizes of some collections and the undesirable dependance of the estimation of polymorphism frequency on its variance, an a ... | 1987 | 3038671 |
| the molecular through ecological genetics of abnormal abdomen. ii. ribosomal dna polymorphism is associated with the abnormal abdomen syndrome in drosophila mercatorum. | restriction endonuclease cleavage analyses of cloned and genomic dna samples indicate that the structure of the dna encoding the large cytoplasmic rnas (rdnas) is altered in drosophila mercatorum lines which exhibit an abnormal abdomen (aa) phenotype. in a majority of the rdna repeat units from aa flies, the 28s coding sequence is interrupted by a large [5-6 kilobase pairs (kbp)] insert. a subclone containing this inserted dna (ins 3) hybridizes primarily to rdna-containing sequences in in situ ... | 1986 | 3007282 |
| the molecular through ecological genetics of abnormal abdomen. iii. tissue-specific differential replication of ribosomal genes modulates the abnormal abdomen phenotype in drosophila mercatorum. | the abnormal abdomen (aa) syndrome in drosophila mercatorum is controlled by two major x-linked genetic elements. we have previously shown that the major x-linked element of aa is associated with the presence of large inserts in the 28s gene of the ribosomal rna (rdna) genes. we show that, in polytene tissue of wild-type d. mercatorum, the uninterrupted rdna repeats are overreplicated relative to interrupted repeats. uninterrupted rdna repeats are also overreplicated in polytene tissue of hybrid ... | 1986 | 2420683 |
| the molecular through ecological genetics of abnormal abdomen in drosophila mercatorum. i. basic genetics. | the abnormal abdomen syndrome (aa) in drosophila mercatorum is characterized by the persistence of juvenilized cuticle on the adult abdomen. the aa phenotype is shown to depend on at least two x-linked genetic elements that are about one map unit apart near the centromeric end of the x chromosome. these two genetic elements are necessary for aa expression; one behaves as a dominant element and the other as a recessive. overlaying these genetic studies upon molecular work reported elsewhere, it i ... | 1985 | 4065544 |
| homogenization of geographical variants at the nontranscribed spacer of rdna in drosophila mercatorum. | rdna nontranscribed spacer (nts) lengths of drosophila mercatorum have been measured in individuals from several geographic regions. individuals from the different geographic subpopulations share some length fragments but are in general distinct. the length differences, both within and between individuals, arise from different copy numbers of a 250-bp repeating unit that is localized to one part of the nts. in addition to the length differences caused by the 250-bp repeat, there is a y chromosom ... | 1985 | 3870866 |
| the maintenance of polymorphism owing to differences in developmental time and competition. | the effect of developmental time on the maintenance of an enzyme polymorphism is analyzed under the assumption that competition exists for a reproductively essential resource. specifically, in laboratory vials drosophila compete for oviposition and pupation sites. this system of competition serves as a prototype for the model with late-eclosing individuals being excluded from the reproductive pool. two mating behaviors are modelled: (i) mating is with individuals from only the same cohort group ... | 1985 | 3880376 |
| behavioral facilitation of reproduction in sexual and parthenogenetic drosophila. | in a normal bisexual laboratory strain of drosophila mercatorum, females housed with either fertile or sterile males lay more eggs than do females housed in pairs or as isolates. females of a derived parthenogenetic strain have suffered genetic loss of this behavioral facilitation of egg production, a loss comparable to the loss of sexual receptivity. despite these losses there has been a large increase in fecundity in the parthenogenetic strain. these findings are compared with those in a parth ... | 1985 | 3964961 |
| studies of enzyme polymorphism in the kamuela population of drosophila mercatorum. iii. effects of variation at the alpha gpd locus and subflight stress on the energy charge and glycolytic intermediate concentrations. | we have employed a "level crossing" strategy to study the primary effects of an enzyme polymorphism in drosophila mercatorum. this strategy consists of following genetic differences across intervening phenotypes to possible fitness effects. in this paper, we report the steady state concentrations of the glycolytic intermediates and the adenylates (intervening phenotypes) in two genotypes (alpha gpd-f, alpha gpd-s) at two stress levels (rest, subflight). we did not detect a genotype or a genotype ... | 1983 | 6618164 |
| studies of enzyme polymorphisms in the kamuela population of drosophila mercatorum. ii. evaluation of glycolytic intermediates. | a simple and effective cryogenic procedure for the extraction of glycolytic intermediates from whole drosophila has been developed. this procedure gives consistent results when a measure (microm/liter/od260) is adopted which corrects for differences in extraction efficiency. using this measure and a homozygous strain of d. mercatorum, there are no significant differences among extracts for the levels of any of the 15 glycolytic intermediate or energy molecules considered. the profile of means is ... | 1982 | 7165691 |
| decay of female sexual behavior under parthenogenesis. | a laboratory strain of drosophila mercatorum has existed for 20 years without males and therefore without natural selection operating to maintain the genetic basis of female mating behavior. the females of this strain have recently experienced a genetic impairment of mating capacity. this observation exemplifies the mode of evolution of vestigial characters and supports muller's theory that random mutation will tend to destroy the genetic basis of a character from which selection has been remove ... | 1982 | 17776711 |
| studies of enzyme polymorphisms in the kamuela population of d. mercatorum. i. estimation of the level of polymorphism. | a kamuela, hawaii, population of drosophila mercatorum was surveyed for enzyme variability. the mean heterozygosity and the proportion of polymorphic loci were estimated as 0.1255 and 0.37, respectively. neither deviates more than one standard error from their respective means for 43 drosophila species (nevo 1978). heterozygosity was distributed across enzyme categories in much the same manner as observed in other species (gillespie and kojima 1968; johnson 1974), and enzymes associated with gly ... | 1981 | 17249102 |
| variation in courtship sounds among three geographical strains of drosophila mercatorum. | sound recordings of courtship in drosophila mercatorum were analyzed with an oscilloscope. sounds in this species consist of two kinds of pulses, referred to as the a and b sounds, respectively. these differ from each other in their oscilloscope pattern and in the behavior accompanying them. a comparative study of three strains from widely separated geographical regions (new york, el salvador, and hawaii) revealed significant differences among strains in the interpulse interval (ipi) of the a so ... | 1980 | 7213309 |
| the unit of selection in drosophila mercatorum. ii. genetic revolution and the origin of coadapted genomes in parthenogenetic strains. | drosophila mercatorum is a sexual species that can reproduce parthenogenetically. previous studies revealed that parthenogenetic strains had "coadapted genomes" with high fitness under parthenogenesis and total homozygosity due to nonadditive and nonmultiplicative fitness interactions between chromosomal segments scattered throughout the genome. to study the evolutionary origins of such coadapted genomes, females from sexual matings in nature were isolated as virgins and challenged to reproduce ... | 1979 | 17248951 |
| genetic recombination and clonal selection in drosophila mercatorum. | discrete and continuous generation unisexual populations were established from parthenogenetic d. mercatorum females heterozygous for five visible loci and one electrophoretic locus, which marked all five major chromosome arms. in the first impaternate generation of the discrete generation population, all thirty-two possible recombinant genotypes for the five visible markers were displayed. however, 99% of these individuals were homozygous for all gene markers due to the predominant mode of part ... | 1978 | 17248829 |
| behavioral differences among isogenic strains of drosophila mercatorum. | mating propensity in eight all-female laboratory lines was measured. the lines are completely isogenic, but each has a different past history. in all cases, mating propensity was significantly lower than in the bisexual controls; in some cases, mating speed was less by a factor of 10. three of the four lines deriving from the same wild strain are not only different from the parent strain but also different from each other. a highly significant difference exists between two strains recently obtai ... | 1977 | 869858 |
| effects of light conditions on mating speed in drosophila mercatorum. | mating speed of flies which have been aged either in the light, in the dark or in a light-and-dark cycle was measured using two strains, rochester (r) and salvador (s), of drosophila mercatorum. a significant difference in mating tendency depending on the condition of pretreatment was found between r and s strains, while both strains showed a similar pattern of the diurnal rhythm in the light-and-dark cycle. compared under the same conditions, s flies usually showed a higher mating speed than r ... | 1976 | 987781 |
| the unit of selection in drosophila mercatorum. i. the interation of selection and meiosis in parthenogenetic strains. | an important problem in population genetics is the determination of the level of genetic organization to which fitness measures can be ascribed that yield an adequate description or prediction of the outcome of selection in populations. to study this problem, we used two strains of drosophila merca torum (s-1-im and o-3-im) that are capable of both sexual and parthenogenetic reproduction, a feature that allows us to experimentally control many factors which affect genetic variability. both s and ... | 1976 | 1261797 |
| selection for mating reluctance in females of a diploid parthenogenetic strain of drosophila mercatorum. | a diploid parthenogenetic strain of drosophila mercatorum was outcrossed to produce genetic variance among the impaternate female offspring. selection experiments were carried out for reluctance of the parthenogenetic females to mate. after only two cycles of selection, a parthenogenetic strain which is significantly less receptive to males from three different bisexual strains was obtained. it was also found that there is some degree of sexual isolation among the three bisexual strains used. th ... | 1973 | 4775749 |
| the genetic system in parthenogenetic strains of drosophila mercatorum. | five parthenogenetic laboratory strains of drosophila mercatorum have been examined for their mode of diploidization in the eggs of females. diploidization occurs either by pronuclear duplication leading to complete homozygosity or by nuclear fusion. if the latter occurs between pronuclei from different secondary oocytes, heterozygosity can be maintained. each of the five strains shows some nuclear fusion and three show significantly different amounts, ranging from about 21% to less than 1%. eve ... | 1973 | 4515936 |
| the population genetics of parthenogenetic strains of drosophila mercatorum : i. one locus model and statistics. | a one locus model has been developed to describe parthenogenetic populations restoring diploidy by central fusion, terminal fusion and gamete duplication. it was found that in the absence of selection all populations become homozygous. with selection, however, it is possible to maintain heterozygotes and homozygotes. the conditions required to yield such an equilibrium are a function of (1) the proportions of the various diploid restoring mechanisms (2) linkage to the kinetochore and (3) the int ... | 1973 | 24425071 |
| isogenicity in parthenogenetic strains of drosophila mercatorum. | | 1969 | 5399250 |
| selection for parthenogenesis in drosophila mercatorum. | | 1967 | 6031599 |