Статті в журналах: "Drosophila Genetics"

1

Schlenke, Todd A., and David J. Begun. "Natural Selection Drives Drosophila Immune System Evolution." Genetics 164, no. 4 (August 1, 2003): 1471–80. http://dx.doi.org/10.1093/genetics/164.4.1471.

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Abstract Evidence from disparate sources suggests that natural selection may often play a role in the evolution of host immune system proteins. However, there have been few attempts to make general population genetic inferences on the basis of analysis of several immune-system-related genes from a single species. Here we present DNA polymorphism and divergence data from 34 genes thought to function in the innate immune system of Drosophila simulans and compare these data to those from 28 nonimmunity genes sequenced from the same lines. Several statistics, including average KA/KS ratio, average silent heterozygosity, and average haplotype diversity, significantly differ between the immunity and nonimmunity genes, suggesting an important role for directional selection in immune system protein evolution. In contrast to data from mammalian immunoglobulins and other proteins, we find no strong evidence for the selective maintenance of protein diversity in Drosophila immune system proteins. This may be a consequence of Drosophila’s generalized innate immune response.

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2

O'Grady, Patrick M. "Whither Drosophila?" Genetics 185, no. 2 (June 2010): 703–5. http://dx.doi.org/10.1534/genetics.110.118232.

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3

Garza, D., M. M. Medhora, and D. L. Hartl. "Drosophila nonsense suppressors: functional analysis in Saccharomyces cerevisiae, Drosophila tissue culture cells and Drosophila melanogaster." Genetics 126, no. 3 (November 1, 1990): 625–37. http://dx.doi.org/10.1093/genetics/126.3.625.

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Abstract Amber (UAG) and opal (UGA) nonsense suppressors were constructed by oligonucleotide site-directed mutagenesis of two Drosophila melanogaster leucine-tRNA genes and tested in yeast, Drosophila tissue culture cells and transformed flies. Suppression of a variety of amber and opal alleles occurs in yeast. In Drosophila tissue culture cells, the mutant tRNAs suppress hsp70:Adh (alcohol dehydrogenase) amber and opal alleles as well as an hsp70:beta-gal (beta-galactosidase) amber allele. The mutant tRNAs were also introduced into the Drosophila genome by P element-mediated transformation. No measurable suppression was seen in histochemical assays for Adhn4 (amber), AdhnB (opal), or an amber allele of beta-galactosidase. Low levels of suppression (approximately 0.1-0.5% of wild type) were detected using an hsp70:cat (chloramphenicol acetyltransferase) amber mutation. Dominant male sterility was consistently associated with the presence of the amber suppressors.

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4

Thomas-Orillard, M., B. Jeune, and G. Cusset. "Drosophila-host genetic control of susceptibility to Drosophila C virus." Genetics 140, no. 4 (August 1, 1995): 1289–95. http://dx.doi.org/10.1093/genetics/140.4.1289.

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Abstract Interactions between Drosophila C virus (DCV) and its natural host, Drosophila melanogaster, were investigated using 15 geographical population samples infected by intraabdominal inoculation. These strains derived from natural populations of D. melanogaster differed in susceptibility to the DCVc. One strain was "partially tolerant". Isofemale lines obtained from one susceptible and one partially tolerant strain were studied. The partially tolerant phenotype was dominant, and there was no difference between F1 progeny of direct and reciprocal crosses. Analysis of F2 progeny showed that neither sex-linked genes nor maternal effects are involved in susceptibility to DCVc. The partially tolerant strain phenotype was dominant and segregated with chromosome III. Two nonexclusive hypotheses are proposed to explain chromosome III gene action.

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5

Klaczko, Louis Bernard, Charles E. Taylor, and Jeffrey R. Powell. "GENETIC VARIATION FOR DISPERSAL BY DROSOPHILA PSEUDOOBSCURA AND DROSOPHILA PERSIMILIS." Genetics 112, no. 2 (February 1, 1986): 229–35. http://dx.doi.org/10.1093/genetics/112.2.229.

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ABSTRACT Release-recapture experiments using Drosophila pseudoobscura and D. persimilis strains of different karyotypes were performed in a heterogeneous environment. The heterogeneity was due to both spatial variation and the species of yeast used to attract the released flies. No karyotypic-specific habitat preferences were detected. However, in all releases, different strains did behave differently with respect to one or both of the heterogeneous factors. These results indicate there is variation for dispersal behavior in these species that is most likely based on genotype-dependent habitat preferences.

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6

Moriyama, E. N., and D. L. Hartl. "Codon usage bias and base composition of nuclear genes in Drosophila." Genetics 134, no. 3 (July 1, 1993): 847–58. http://dx.doi.org/10.1093/genetics/134.3.847.

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Abstract The nuclear genes of Drosophila evolve at various rates. This variation seems to correlate with codon-usage bias. In order to elucidate the determining factors of the various evolutionary rates and codon-usage bias in the Drosophila nuclear genome, we compared patterns of codon-usage bias with base compositions of exons and introns. Our results clearly show the existence of selective constraints at the translational level for synonymous (silent) sites and, on the other hand, the neutrality or near neutrality of long stretches of nucleotide sequence within noncoding regions. These features were found for comparisons among nuclear genes in a particular species (Drosophila melanogaster, Drosophila pseudoobscura and Drosophila virilis) as well as in a particular gene (alcohol dehydrogenase) among different species in the genus Drosophila. The patterns of evolution of synonymous sites in Drosophila are more similar to those in the prokaryotes than they are to those in mammals. If a difference in the level of expression of each gene is a main reason for the difference in the degree of selective constraint, the evolution of synonymous sites of Drosophila genes would be sensitive to the level of expression among genes and would change as the level of expression becomes altered in different species. Our analysis verifies these predictions and also identifies additional selective constraints at the translational level in Drosophila.

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7

Wu, C. Y., J. Mote, and M. D. Brennan. "Tissue-specific expression phenotypes of Hawaiian Drosophila Adh genes in Drosophila melanogaster transformants." Genetics 125, no. 3 (July 1, 1990): 599–610. http://dx.doi.org/10.1093/genetics/125.3.599.

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Abstract Interspecific differences in the tissue-specific patterns of expression displayed by the alcohol dehydrogenase (Adh) genes within the Hawaiian picture-winged Drosophila represent a rich source of evolutionary variation in gene regulation. Study of the cis-acting elements responsible for regulatory differences between Adh genes from various species is greatly facilitated by analyzing the behavior of the different Adh genes in a homogeneous background. Accordingly, the Adh gene from Drosophila grimshawi was introduced into the germ line of Drosophila melanogaster by means of P element-mediated transformation, and transformants carrying this gene were compared to transformants carrying the Adh genes from Drosophila affinidisjuncta and Drosophila hawaiiensis. The results indicate that the D. affinidisjuncta and D. grimshawi genes have relatively higher levels of expression and broader tissue distribution of expression than the D. hawaiiensis gene in larvae. All three genes are expressed at similar overall levels in adults, with differences in tissue distribution of enzyme activity corresponding to the pattern in the donor species. However, certain systematic differences between Adh gene expression in transformants and in the Hawaiian Drosophila are noted along with tissue-specific position effects in some cases. The implications of these findings for the understanding of evolved regulatory variation are discussed.

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8

Provine, W. B. "Alfred Henry Sturtevant and crosses between Drosophila melanogaster and Drosophila simulans." Genetics 129, no. 1 (September 1, 1991): 1–5. http://dx.doi.org/10.1093/genetics/129.1.1.

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9

Wolstenholme, David R., and Douglas O. Clary. "SEQUENCE EVOLUTION OF DROSOPHILA MITOCHONDRIAL DNA." Genetics 109, no. 4 (April 1, 1985): 725–44. http://dx.doi.org/10.1093/genetics/109.4.725.

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ABSTRACT We have compared nucleotide sequences of corresponding segments of the mitochondrial DNA (mtDNA) molecules of Drosophila yakuba and Drosophila melanogaster, which contain the genes for six proteins and seven tRNAs. The overall frequency of substitution between the nucleotide sequences of these protein genes is 7.2%. As was found for mtDNAs from closely related mammals, most substitutions (86%) in Drosophila mitochondrial protein genes do not result in an amino acid replacement. However, the frequencies of transitions and transversions are approximately equal in Drosophila mtDNAs, which is in contrast to the vast excess of transitions over transversions in mammalian mtDNAs. In Drosophila mtDNAs the frequency of C ↔ T substitutions per codon in the third position is 2.5 times greater among codons of two-codon families than among codons of four-codon families; this is contrary to the hypothesis that third position silent substitutions are neutral in regard to selection. In the third position of codons of four-codon families transversions are 4.6 times more frequent than transitions and A ↔ T substitutions account for 86% of all transversions. Ninety-four percent of all codons in the Drosophila mtDNA segments analyzed end in A or T. However, as this alone cannot account for the observed high frequency of A ↔ T substitutions there must be either a disproportionately high rate of A ↔ T mutation in Drosophila mtDNA or selection bias for the products of A ↔ T mutation.—Consideration of the frequencies of interchange of AGA and AGT codons in the corresponding D. yakuba and D. melanogaster mitochondrial protein genes provides strong support for the view that AGA specifies serine in the Drosophila mitochondrial genetic code.

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10

Sofer, W., and L. Tompkins. "Drosophila genetics in the classroom." Genetics 136, no. 1 (January 1, 1994): 417–22. http://dx.doi.org/10.1093/genetics/136.1.417.

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Abstract Drosophila has long been useful for demonstrating the principles of classical Mendelian genetics in the classroom. In recent years, the organism has also helped students understand biochemical and behavioral genetics. In this connection, this article describes the development of a set of integrated laboratory exercises and descriptive materials--a laboratory module--in biochemical genetics for use by high-school students. The module focuses on the Adh gene and its product, the alcohol dehydrogenase enzyme. Among other activities, students using the module get to measure alcohol tolerance and to assay alcohol dehydrogenase activity in Adh-negative and -positive flies. To effectively present the module in the classroom, teachers attend a month-long Dissemination Institute in the summer. During this period, they learn about other research activities that can be adapted for classroom use. One such activity that has proved popular with teachers and students utilizes Drosophila to introduce some of the concepts of behavioral genetics to the high-school student. By establishing closer interactions between high-school educators and research scientists, the gulf between the two communities can begin to be bridged. It is anticipated that the result of a closer relationship will be that the excitement and creativity of science will be more effectively conveyed to students.

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11

Crow, James F., Dan Lindsley, and John Lucchesi. "Edward Novitski: Drosophila Virtuoso." Genetics 174, no. 2 (October 2006): 549–53. http://dx.doi.org/10.1534/genetics.104.65953.

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12

Germani, Federico, Cora Bergantinos, and Laura A. Johnston. "Mosaic Analysis in Drosophila." Genetics 208, no. 2 (January 29, 2018): 473–90. http://dx.doi.org/10.1534/genetics.117.300256.

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13

Small, Stephen, and David N. Arnosti. "Transcriptional Enhancers in Drosophila." Genetics 216, no. 1 (September 2020): 1–26. http://dx.doi.org/10.1534/genetics.120.301370.

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Key discoveries in Drosophila have shaped our understanding of cellular “enhancers.” With a special focus on the fly, this chapter surveys properties of these adaptable cis-regulatory elements, whose actions are critical for the complex spatial/temporal transcriptional regulation of gene expression in metazoa. The powerful combination of genetics, molecular biology, and genomics available in Drosophila has provided an arena in which the developmental role of enhancers can be explored. Enhancers are characterized by diverse low- or high-throughput assays, which are challenging to interpret, as not all of these methods of identifying enhancers produce concordant results. As a model metazoan, the fly offers important advantages to comprehensive analysis of the central functions that enhancers play in gene expression, and their critical role in mediating the production of phenotypes from genotype and environmental inputs. A major challenge moving forward will be obtaining a quantitative understanding of how these cis-regulatory elements operate in development and disease.

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14

Mateos, Mariana, Sergio J. Castrezana, Becky J. Nankivell, Anne M. Estes, Therese A. Markow, and Nancy A. Moran. "Heritable Endosymbionts of Drosophila." Genetics 174, no. 1 (June 18, 2006): 363–76. http://dx.doi.org/10.1534/genetics.106.058818.

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15

Sokolowski, Marla B. "Drosophila: Genetics meets behaviour." Nature Reviews Genetics 2, no. 11 (November 2001): 879–90. http://dx.doi.org/10.1038/35098592.

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16

Mahowald, A. P., and P. A. Hardy. "Genetics of Drosophila Embryogenesis." Annual Review of Genetics 19, no. 1 (December 1985): 149–77. http://dx.doi.org/10.1146/annurev.ge.19.120185.001053.

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17

Wilkins, Adam S. "Developmental genetics of drosophila." BioEssays 21, no. 8 (July 29, 1999): 710–11. http://dx.doi.org/10.1002/(sici)1521-1878(199908)21:8<710::aid-bies11>3.0.co;2-d.

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18

Leung, Wilson, Christopher D. Shaffer, Taylor Cordonnier, Jeannette Wong, Michelle S. Itano, Elizabeth E. Slawson Tempel, Elmer Kellmann, et al. "Evolution of a Distinct Genomic Domain in Drosophila: Comparative Analysis of the Dot Chromosome in Drosophila melanogaster and Drosophila virilis." Genetics 185, no. 4 (May 17, 2010): 1519–34. http://dx.doi.org/10.1534/genetics.110.116129.

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19

Vlachou, Dina, Mary Konsolalti, Peter P. Tolias, Fotis C. Kafatos, and Katia Komitopoulou. "The Autosomal Chorion Locus of the Medfly Ceratitis capitata. I. Conserved Synteny, Amplification and Tissue Specificity but Sequence Divergence and Altered Temporal Regulation." Genetics 147, no. 4 (December 1, 1997): 1829–42. http://dx.doi.org/10.1093/genetics/147.4.1829.

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Abstract We report the isolation, full sequence characterization, amplification and expression properties of medfly chorion genes corresponding to the autosomal chorion locus of Drosophila. These genes are found adjacent to the paramyosin gene and are organized in the same order and tandem orientation as their Drosophila homologues, although they are spaced further apart. They show substantial sequence divergence from their Drosophila homologues, including novel peptide repeats and a new spacing of the tyrosines, which are known to be cross-linked in Dipteran chorion. The genes are amplified and expressed during oogenesis, as in Drosophila. Three of them are expressed in the same relative temporal order as in Drosophila but the fourth gene, the homologue of s15, shows a clear shift to an earlier expression period. This is the first known instance of changed temporal regulation in dipteran chorion genes.

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20

O'Neil, M. T., and J. M. Belote. "Interspecific comparison of the transformer gene of Drosophila reveals an unusually high degree of evolutionary divergence." Genetics 131, no. 1 (May 1, 1992): 113–28. http://dx.doi.org/10.1093/genetics/131.1.113.

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Abstract The transformer (tra) gene of Drosophila melanogaster occupies an intermediate position in the regulatory pathway controlling all aspects of somatic sexual differentiation. The female-specific expression of this gene's function is regulated by the Sex lethal (Sxl) gene, through a mechanism involving sex-specific alternative splicing of tra pre-mRNA. The tra gene encodes a protein that is thought to act in conjunction with the transformer-2 (tra-2) gene product to control the sex-specific processing of doublesex (dsx) pre-mRNA. The bifunctional dsx gene carries out opposite functions in the two sexes, repressing female differentiation in males and repressing male differentiation in females. Here we report the results from an evolutionary approach to investigate tra regulation and function, by isolating the tra-homologous genes from selected Drosophila species, and then using the interspecific DNA sequence comparisons to help identify regions of functional significance. The tra-homologous genes from two Sophophoran subgenus species, Drosophila simulans and Drosophila erecta, and two Drosophila subgenus species, Drosophila hydei and Drosophila virilis, were cloned, sequenced and compared to the D. melanogaster tra gene. This comparison reveals an unusually high degree of evolutionary divergence among the tra coding sequences. These studies also highlight a highly conserved sequence within intron one that probably defines a cis-acting regulator of the sex-specific alternative splicing event.

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21

Bentley, Alyssa, Bridget MacLennan, Jonathan Calvo, and Charles R. Dearolf. "Targeted Recovery of Mutations in Drosophila." Genetics 156, no. 3 (November 1, 2000): 1169–73. http://dx.doi.org/10.1093/genetics/156.3.1169.

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Abstract Reverse genetic techniques will be necessary to take full advantage of the genomic sequence data for Drosophila and other experimental organisms. To develop a method for the targeted recovery of mutations, we combined an EMS chemical mutagenesis regimen with mutation detection by denaturing high performance liquid chromatography (DHPLC). We recovered mutant strains at the high rate of ∼4.8 mutations/kb for every 1000 mutagenized chromosomes from a screen for new mutations in the Drosophila awd gene. Furthermore, we observed that the EMS mutational spectrum in Drosophila germ cells shows a strong preference for 5′-PuG-3′ sites, and for G/C within a stretch of three or more G/C base pairs. Our method should prove useful for targeted mutagenesis screens in Drosophila and other genetically tractable organisms and for more precise studies of mutagenesis and DNA repair mechanisms.

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22

SINGH, PRANVEER, and BASHISTH N. SINGH. "Population genetics of Drosophila ananassae." Genetics Research 90, no. 5 (October 2008): 409–19. http://dx.doi.org/10.1017/s0016672308009737.

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SummaryDrosophila ananassae Doleschall is a cosmopolitan and domestic species. It occupies a unique status among Drosophila species due to certain peculiarities in its genetic behaviour and is of common occurrence in India. Quantitative genetics of sexual and non-sexual traits provided evidence for genetic control of these traits. D. ananassae exhibits high level of chromosomal polymorphism in its natural populations. Indian natural populations of D. ananassae show geographic differentiation of inversion polymorphism due to their adaptation to varying environments and natural selection operates to maintain three cosmopolitan inversions. Populations do not show divergence on temporal scale, an evidence for rigid polymorphism. D. ananassae populations show substantial degree of sub-structuring and exist as semi-isolated populations. Gene flow is low despite co-transportation with human goods. There is persistence of cosmopolitan inversions when populations are transferred to laboratory conditions, which suggests that heterotic buffering is associated with these inversions in D. ananassae. Populations collected from similar environmental conditions that initially show high degree of genetic similarity have diverged to different degrees in laboratory environment. This randomness could be due to genetic drift. Interracial hybridization does not lead to breakdown of heterosis associated with cosmopolitan inversions, which shows that there is lack of genetic co-adaptation in D. ananassae. Linkage disequilibrium between independent inversions in laboratory populations has often been observed, which is likely to be due to suppression of crossing-over and random genetic drift. No evidence for chromosomal interactions has been found in natural and laboratory populations of D. ananassae. This strengthens the previous suggestion that there is lack of genetic co-adaptation in D. ananassae.

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23

Morton, R. A. "Evolution of Drosophila insecticide resistance." Genome 36, no. 1 (February 1, 1993): 1–7. http://dx.doi.org/10.1139/g93-001.

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The impact of insecticide resistance is well documented. It includes the toxic effects of pesticides on the environment and the cost of the increased amounts of insecticides required to effectively control resistant insects. Resistance evolves by the selection of genes that confer tolerance to insecticides. Several resistance genes have been identified and cloned in Drosophila, including genes for mutant target molecules and genes that increase insecticide degradation. Drosophila is a useful system to understand the evolution of quantitative traits in general as well as the population genetics of insecticide resistance. Through it, we may hope to understand the relationship between discrete genetic change and continuously varying characters. In addition, molecular genetic techniques developed using Drosophila can eventually be transferred to other insects in order to help control pest populations.Key words: insecticide resistance, evolution of tolerance, selection of resistant genes, molecular genetics, Drosophila.

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24

VAN DER LINDE, KIM, DAVID HOULE, GREG S. SPICER, and SCOTT J. STEPPAN. "A supermatrix-based molecular phylogeny of the family Drosophilidae." Genetics Research 92, no. 1 (February 2010): 25–38. http://dx.doi.org/10.1017/s001667231000008x.

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SummaryThe genus Drosophila is diverse and heterogeneous and contains a large number of easy-to-rear species, so it is an attractive subject for comparative studies. The ability to perform such studies is currently compromised by the lack of a comprehensive phylogeny for Drosophila and related genera. The genus Drosophila as currently defined is known to be paraphyletic with respect to several other genera, but considerable uncertainty remains about other aspects of the phylogeny. Here, we estimate a phylogeny for 176 drosophilid (12 genera) and four non-drosophilid species, using gene sequences for up to 13 different genes per species (average: 4333 bp, five genes per species). This is the most extensive set of molecular data on drosophilids yet analysed. Phylogenetic analyses were conducted with maximum-likelihood (ML) and Bayesian approaches. Our analysis confirms that the genus Drosophila is paraphyletic with 100% support in the Bayesian analysis and 90% bootstrap support in the ML analysis. The subgenus Sophophora, which includes Drosophila melanogaster, is the sister clade of all the other subgenera as well as of most species of six other genera. This sister clade contains two large, well-supported subclades. The first subclade contains the Hawaiian Drosophila, the genus Scaptomyza, and the virilis-repleta radiation. The second contains the immigrans-tripunctata radiation as well as the genera Hirtodrosophila (except Hirtodrosophila duncani), Mycodrosophila, Zaprionus and Liodrosophila. We argue that these results support a taxonomic revision of the genus Drosophila.

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25

Spradling, Allan C., Dianne Stern, Amy Beaton, E. Jay Rhem, Todd Laverty, Nicole Mozden, Sima Misra, and Gerald M. Rubin. "The Berkeley Drosophila Genome Project Gene Disruption Project: Single P-Element Insertions Mutating 25% of Vital Drosophila Genes." Genetics 153, no. 1 (September 1, 1999): 135–77. http://dx.doi.org/10.1093/genetics/153.1.135.

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AbstractA fundamental goal of genetics and functional genomics is to identify and mutate every gene in model organisms such as Drosophila melanogaster. The Berkeley Drosophila Genome Project (BDGP) gene disruption project generates single P-element insertion strains that each mutate unique genomic open reading frames. Such strains strongly facilitate further genetic and molecular studies of the disrupted loci, but it has remained unclear if P elements can be used to mutate all Drosophila genes. We now report that the primary collection has grown to contain 1045 strains that disrupt more than 25% of the estimated 3600 Drosophila genes that are essential for adult viability. Of these P insertions, 67% have been verified by genetic tests to cause the associated recessive mutant phenotypes, and the validity of most of the remaining lines is predicted on statistical grounds. Sequences flanking >920 insertions have been determined to exactly position them in the genome and to identify 376 potentially affected transcripts from collections of EST sequences. Strains in the BDGP collection are available from the Bloomington Stock Center and have already assisted the research community in characterizing >250 Drosophila genes. The likely identity of 131 additional genes in the collection is reported here. Our results show that Drosophila genes have a wide range of sensitivity to inactivation by P elements, and provide a rationale for greatly expanding the BDGP primary collection based entirely on insertion site sequencing. We predict that this approach can bring >85% of all Drosophila open reading frames under experimental control.

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26

Whiting, J. H., M. D. Pliley, J. L. Farmer, and D. E. Jeffery. "In situ hybridization analysis of chromosomal homologies in Drosophila melanogaster and Drosophila virilis." Genetics 122, no. 1 (May 1, 1989): 99–109. http://dx.doi.org/10.1093/genetics/122.1.99.

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Abstract Twenty-four biotin-labeled recombinant-DNA probes which contained putative unique-sequence Drosophila melanogaster DNA were hybridized to larval salivary-gland chromosomes of D. melanogaster and Drosophila virilis. All probes hybridized to D. melanogaster chromosomes at the expected sites. However, one probe hybridized to at least 16 additional sites, and one hybridized to one additional site. Thirteen probes hybridized strongly to D. virilis chromosomes, four hybridized weakly and infrequently, and seven did not hybridize. Probes representing two multigene families (beta-tubulin and yolk-protein) hybridized as would be expected if all sites had been conserved in the two species on the same chromosomal elements. The multiple hybridization sites of a third probe which may represent a multigene family were also conserved. The results were consistent with H.J. Muller's proposal that chromosomal elements have been conserved during evolution of this genus.

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27

Graze, Rita M., Olga Barmina, Daniel Tufts, Elena Naderi, Kristy L. Harmon, Maria Persianinova, and Sergey V. Nuzhdin. "New Candidate Genes for Sex-Comb Divergence Between Drosophila mauritiana and Drosophila simulans." Genetics 176, no. 4 (June 11, 2007): 2561–76. http://dx.doi.org/10.1534/genetics.106.067686.

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28

Marquez, Raymond M., Matthew A. Singer, Norma T. Takaesu, W. Ross Waldrip, Yevgenya Kraytsberg та Stuart J. Newfeld. "Transgenic Analysis of the Smad Family of TGF-β Signal Transducers in Drosophila melanogaster Suggests New Roles and New Interactions Between Family Members". Genetics 157, № 4 (1 квітня 2001): 1639–48. http://dx.doi.org/10.1093/genetics/157.4.1639.

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Abstract Smad signal transducers are required for transforming growth factor-β-mediated developmental events in many organisms including humans. However, the roles of individual human Smad genes (hSmads) in development are largely unknown. Our hypothesis is that an hSmad performs developmental roles analogous to those of the most similar Drosophila Smad gene (dSmad). We expressed six hSmad and four dSmad transgenes in Drosophila melanogaster using the Gal4/UAS system and compared their phenotypes. Phylogenetically related human and Drosophila Smads induced similar phenotypes supporting the hypothesis. In contrast, two nearly identical hSmads generated distinct phenotypes. When expressed in wing imaginal disks, hSmad2 induced oversize wings while hSmad3 induced cell death. This observation suggests that a very small number of amino acid differences, between Smads in the same species, confer distinct developmental roles. Our observations also suggest new roles for the dSmads, Med and Dad, in dActivin signaling and potential interactions between these family members. Overall, the study demonstrates that transgenic methods in Drosophila can provide new information about non-Drosophila members of developmentally important multigene families.

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29

Zeng, L. W., and R. S. Singh. "The genetic basis of Haldane's rule and the nature of asymmetric hybrid male sterility among Drosophila simulans, Drosophila mauritiana and Drosophila sechellia." Genetics 134, no. 1 (May 1, 1993): 251–60. http://dx.doi.org/10.1093/genetics/134.1.251.

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Abstract Haldane's rule (i.e., the preferential hybrid sterility and inviability of heterogametic sex) has been known for 70 years, but its genetic basis, which is crucial to the understanding of the process of species formation, remains unclear. In the present study, we have investigated the genetic basis of hybrid male sterility using Drosophila simulans, Drosophila mauritiana and Drosophila sechellia. An introgression of D. sechellia Y chromosome into a fairly homogenous background of D. simulans did not show any effect of the introgressed Y on male sterility. The substitution of D. simulans Y chromosome into D. sechellia, and both reciprocal Y chromosome substitutions between D. simulans and D. mauritiana were unsuccessful. Introgressions of cytoplasm between D. simulans and D. mauritiana (or D. sechellia) also did not have any effect on hybrid male sterility. These results rule out the X-Y interaction hypothesis as a general explanation of Haldane's rule in this species group and indicate an involvement of an X-autosome interaction. Models of symmetrical and asymmetrical X-autosome interaction have been developed which explain the Y chromosome substitution results and suggest that evolution of interactions between different genetic elements in the early stages of speciation is more likely to be of an asymmetrical nature. The model of asymmetrical X-autosome interaction also predicts that different sets of interacting genes may be involved in different pairs of related species and can account for the observation that hybrid male sterility in many partially isolated species is often nonreciprocal or unidirectional.

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30

Fatmawati, Diani, Maryam Saleem, Iin Hindun, Indah Permatasari, Solikhah Solikhah, Diana Khoiroh, and Ahmad Fauzi. "Drosophila Melanogaster Utilization in Genetics Lectures: Innovations that Need to be Optimized." JURNAL PENDIDIKAN SAINS (JPS) 10, no. 1 (May 17, 2022): 22. http://dx.doi.org/10.26714/jps.10.1.2022.22-27.

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Drosophila melanogaster is a popular model organism that plays a role in the development of Genetics research and learning. The purpose of this study was to map Genetics lecture activities in Indonesia based on the utilization of Drosophila melanogaster during practicum activities. The data was collected using Google Form-based questionnaire analyzed using descriptive statistical analysis. A total of 113 alumni from 39 universities in Indonesia were involved as participants. The results informed that 77% of institutions had conducted Genetic Practicums and more than half had used Drosophila melanogaster. However, optimizing the use of these organisms in learning needs to be improved because the use of Drosophila melanogaster is still limited to morphological, chromosome, life cycle, and inheritance pattern observations.

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31

Rong, Yikang S., and Kent G. Golic. "A Targeted Gene Knockout in Drosophila." Genetics 157, no. 3 (March 1, 2001): 1307–12. http://dx.doi.org/10.1093/genetics/157.3.1307.

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Abstract We previously described a method for targeted homologous recombination at the yellow gene of Drosophila melanogaster. Because only a single gene was targeted, further work was required to show whether the method could be extended to become generally useful for gene modification in Drosophila. We have now used this method to produce a knockout of the autosomal pugilist gene by homologous recombination between the endogenous locus and a 2.5-kb DNA fragment. This was accomplished solely by tracking the altered genetic linkage of an arbitrary marker gene as the targeting DNA moved from chromosome X or 2 to chromosome 3. The results indicate that this method of homologous recombination is likely to be generally useful for Drosophila gene targeting.

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32

Arkhipova, I. R. "Promoter elements in Drosophila melanogaster revealed by sequence analysis." Genetics 139, no. 3 (March 1, 1995): 1359–69. http://dx.doi.org/10.1093/genetics/139.3.1359.

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Abstract A Drosophila Promoter Database containing 252 independent Drosophila melanogaster promoter entries has been compiled. The database and its subsets have been searched for overrepresented sequences. The analysis reveals that the proximal promoter region displays the most dramatic nucleotide sequence irregularities and exhibits a tripartite structure, consisting of TATA at -25/-30 bp, initiator (Inr) at +/- 5 bp and a novel class of downstream elements at +20/+30 bp from the RNA start site. These latter elements are also strand-specific. However, they differ from TATA and Inr in several aspects: (1) they are represented not by a single, but by multiple sequences, (2) they are shorter, (3) their position is less strictly fixed with respect to the RNA start site, (4) they emerge as a characteristic feature of Drosophila promoters and (5) some of them are strongly overrepresented in the TATA-less, but not TATA-containing, subset. About one-half of known Drosophila promoters can be classified as TATA-less. The overall sequence organization of the promoter region is characterized by an extended region with an increase in GC-content and a decrease in A, which contains a number of binding sites for Drosophila transcription factors.

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33

Olsen, DeAnne S., Barbara Jordan, Dreeny Chen, Ronald C. Wek та Douglas R. Cavener. "Isolation of the Gene Encoding the Drosophila melanogaster Homolog of the Saccharomyces cerevisiae GCN2 eIF-2α Kinase". Genetics 149, № 3 (1 липня 1998): 1495–509. http://dx.doi.org/10.1093/genetics/149.3.1495.

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Abstract Genomic and cDNA clones homologous to the yeast GCN2 eIF-2α kinase (yGCN2) were isolated from Drosophila melanogaster. The identity of the Drosophila GCN2 (dGCN2) gene is supported by the unique combination of sequence encoding a protein kinase catalytic domain and a domain homologous to histidyl-tRNA synthetase and by the ability of dGCN2 to complement a deletion mutant of the yeast GCN2 gene. Complementation of Δgcn2 in yeast by dGCN2 depends on the presence of the critical regulatory phosphorylation site (serine 51) of eIF-2α. dGCN2 is composed of 10 exons encoding a protein of 1589 amino acids. dGCN2 mRNA is expressed throughout Drosophila development and is particularly abundant at the earliest stages of embryogenesis. The dGCN2 gene was cytogenetically and physically mapped to the right arm of the third chromosome at 100C3 in STS Dm2514. The discovery of GCN2 in higher eukaryotes is somewhat unexpected given the marked differences between the amino acid biosynthetic pathways of yeast vs. Drosophila and other higher eukaryotes. Despite these differences, the presence of GCN2 in Drosophila suggests at least partial conservation from yeast to multicellular organisms of the mechanisms responding to amino acid deprivation.

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34

Banerjee, Surya, Shimshon Benji, Sarah Liberow, and Josefa Steinhauer. "Using Drosophila melanogaster To Discover Human Disease Genes: An Educational Primer for Use with “Amyotrophic Lateral Sclerosis Modifiers in Drosophila Reveal the Phospholipase D Pathway as a Potential Therapeutic Target”." Genetics 216, no. 3 (November 2020): 633–41. http://dx.doi.org/10.1534/genetics.120.303495.

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Since the dawn of the 20th century, the fruit fly Drosophila melanogaster has been used as a model organism to understand the nature of genes and how they control development, behavior, and physiology. One of the most powerful experimental approaches employed in Drosophila is the forward genetic screen. In the 21st century, genome-wide screens have become popular tools for identifying evolutionarily conserved genes involved in complex human diseases. In the accompanying article “Amyotrophic Lateral Sclerosis Modifiers in Drosophila Reveal the Phospholipase D Pathway as a Potential Therapeutic Target,” Kankel and colleagues describe a forward genetic modifier screen to discover factors that contribute to the severe neurodegenerative disease amyotrophic lateral sclerosis (ALS). This primer briefly traces the history of genetic screens in Drosophila and introduces students to ALS. We then provide a set of guided reading questions to help students work through the data presented in the research article. Finally, several ideas for literature-based research projects are offered as opportunities for students to expand their appreciation of the potential scope of genetic screens. The primer is intended to help students and instructors thoroughly examine a current study that uses forward genetics in Drosophila to identify human disease genes.

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35

Zouros, E. "Advances in the genetics of reproductive isolation in Drosophila." Genome 31, no. 1 (January 1, 1989): 211–20. http://dx.doi.org/10.1139/g89-036.

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Speciation genetics is defined as the study of genetic events and processes that differentiate the probabilities that genetic material from individual members of a population will co-occur in individuals of some future generation. It follows that phenotypic attributes that contribute to this differentiation of probabilities (e.g., mating preferences, sterility, or infertility of individuals from certain types of matings) constitute the phenotype of speciation, and genetic loci that may affect these phenotypic attributes can be considered as speciation genes. The literature on genetic differences between hybridizable species of Drosophila that are responsible for morphological differences, mating preferences, hybrid inviability, and hybrid sterility are reviewed with special reference to the species pair D. mojavensis – D. arizonensis. The case for the involvement of karyotypic changes in speciation in rodents is briefly discussed. It is concluded that no major advance has been made in the speciation genetics of Drosophila since Dobzhansky initiated the field 40 years ago. Yet, the identification of several gene loci that cause hybrid inviability or sterility may open the way to the understanding of reproductive isolation at the molecular level. It is not clear whether this approach will lead to general molecular mechanisms underlying the speciation process.Key words: speciation genetics, hybrid sterility, reproductive isolation, Drosophila.

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36

Lo, P. C., D. Roy, and S. M. Mount. "Suppressor U1 snRNAs in Drosophila." Genetics 138, no. 2 (October 1, 1994): 365–78. http://dx.doi.org/10.1093/genetics/138.2.365.

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Abstract Although the role of U1 small nuclear RNAs (snRNAs) in 5' splice site recognition is well established, suppressor U1 snRNAs active in intact multicellular animals have been lacking. Here we describe suppression of a 5' splice site mutation in the Drosophila melanogaster white gene (wDR18) by compensatory changes in U1 snRNA. Mutation of positions -1 and +6 of the 5' splice site of the second intron (ACG[GTGAGT to ACC]GTGAGC) results in the accumulation of RNA retaining this 74-nucleotide intron in both transfected cells and transgenic flies. U1-3G, a suppressor U1 snRNA which restores base-pairing at position +6 of the mutant intron, increases the ratio of spliced to unspliced wDR18 RNA up to fivefold in transfected Schneider cells and increases eye pigmentation in wDR18 flies. U1-9G, which targets position -1, suppresses wDR18 in transfected cells less well. U1-3G,9G has the same effect as U1-3G although it accumulates to lower levels. Suppression of wDR18 has revealed that the U1b embryonic variant (G134 to U) is active in Schneider cells and pupal eye discs. However, the combination of 9G with 134U leads to reduced accumulation of both U1b-9G and U1b-3G,9G, possibly because nucleotides 9 and 134 both participate in a potential long-range intramolecular base-pairing interaction. High levels of functional U1-3G suppressor reduce both viability and fertility in transformed flies. These results show that, despite the difficulties inherent in stably altering splice site selection in multicellular organisms, it is possible to obtain suppressor U1 snRNAs in flies.

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37

Charlesworth, B., C. H. Langley, and P. D. Sniegowski. "Transposable Element Distributions in Drosophila." Genetics 147, no. 4 (December 1, 1997): 1993–95. http://dx.doi.org/10.1093/genetics/147.4.1993.

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38

Biémont, C., A. Tsitrone, C. Vieira, and C. Hoogland. "Transposable Element Distribution in Drosophila." Genetics 147, no. 4 (December 1, 1997): 1997–99. http://dx.doi.org/10.1093/genetics/147.4.1997.

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39

Mackay, Trudy F. C., Richard F. Lyman, and Faye Lawrence. "Polygenic Mutation in Drosophila melanogaster." Genetics 170, no. 4 (June 8, 2005): 1723–35. http://dx.doi.org/10.1534/genetics.104.032581.

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40

Heier, Christoph, and Ronald P. Kühnlein. "Triacylglycerol Metabolism in Drosophila melanogaster." Genetics 210, no. 4 (December 2018): 1163–84. http://dx.doi.org/10.1534/genetics.118.301583.

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41

Maruyama, K., K. D. Schoor, and D. L. Hartl. "Identification of nucleotide substitutions necessary for trans-activation of mariner transposable elements in Drosophila: analysis of naturally occurring elements." Genetics 128, no. 4 (August 1, 1991): 777–84. http://dx.doi.org/10.1093/genetics/128.4.777.

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Abstract Six copies of the mariner element from the genomes of Drosophila mauritiana and Drosophila simulans were chosen at random for DNA sequencing and functional analysis and compared with the highly active element Mos1 and the inactive element peach. All elements were 1286 base pairs in length, but among them there were 18 nucleotide differences. As assayed in Drosophila melanogaster, three of the elements were apparently nonfunctional, two were marginally functional, and one had moderate activity that could be greatly increased depending on the position of the element in the genome. Both molecular (site-directed mutagenesis) and evolutionary (cladistic analysis) techniques were used to analyze the functional effects of nucleotide substitutions. The nucleotide sequence of the element is the primary determinant of function, though the activity level of elements is profoundly influenced by position effects. Cladistic analysis of the sequences has identified a T----A transversion at position 1203 (resulting in a Phe----Leu amino acid replacement in the putative transposase) as being primarily responsible for the low activity of the barely functional elements. Use of the sequences from the more distantly related species, Drosophila yakuba and Drosophila teissieri, as outside reference species, indicates that functional mariner elements are ancestral and argues against their origination by a novel mutation or by recombination among nonfunctional elements.

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42

Moriyama, E. N., and T. Gojobori. "Rates of synonymous substitution and base composition of nuclear genes in Drosophila." Genetics 130, no. 4 (April 1, 1992): 855–64. http://dx.doi.org/10.1093/genetics/130.4.855.

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Abstract We compared the rates of synonymous (silent) substitution among various genes in a number of species of Drosophila. First, we found that even for a particular gene, the rate of synonymous substitution varied considerably with Drosophila lineages. Second, we showed a large variation in synonymous substitution rates among nuclear genes in Drosophila. These rates of synonymous substitution were correlated negatively with C content and positively with A content at the third codon positions. Nucleotide sequences were also compared between pseudogenes and their functional homologs. The C content of the pseudogenes was lower than that of the functional genes and the A content of the former was higher than that of the latter. Because the synonymous substitution for functional genes and the nucleotide substitution for pseudogenes are exempted from any selective constraint at the protein level, these observations could be explained by a biased pattern of mutation in the Drosophila nuclear genome. Such a bias in the mutation pattern may affect the molecular clock (local clock) of each nuclear gene of each species. Finally, we obtained the average rates of synonymous substitution for three gene groups in Drosophila; 11.0 x 10(-9), 17.5 x 10(-9) and 27.1 x 10(-9)/site/year.

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43

Ruiz, M. Fernanda, M. Rosario Esteban, Carmen Doñoro, Clara Goday, and Lucas Sánchez. "Evolution of Dosage Compensation in Diptera: The Gene maleless Implements Dosage Compensation in Drosophila (Brachycera Suborder) but Its Homolog in Sciara (Nematocera Suborder) Appears to Play No Role in Dosage Compensation." Genetics 156, no. 4 (December 1, 2000): 1853–65. http://dx.doi.org/10.1093/genetics/156.4.1853.

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Abstract In Drosophila melanogaster and in Sciara ocellaris dosage compensation occurs by hypertranscription of the single male X chromosome. This article reports the cloning and characterization in S. ocellaris of the gene homologous to maleless (mle) of D. melanogaster, which implements dosage compensation. The Sciara mle gene produces a single transcript, encoding a helicase, which is present in both male and female larvae and adults and in testes and ovaries. Both Sciara and Drosophila MLE proteins are highly conserved. The affinity-purified antibody to D. melanogaster MLE recognizes the S. ocellaris MLE protein. In contrast to Drosophila polytene chromosomes, where MLE is preferentially associated with the male X chromosome, in Sciara MLE is found associated with all chromosomes. Anti-MLE staining of Drosophila postblastoderm male embryos revealed a single nuclear dot, whereas Sciara male and female embryos present multiple intranuclear staining spots. This expression pattern in Sciara is also observed before blastoderm stage, when dosage compensation is not yet set up. The affinity-purified antibodies against D. melanogaster MSL1, MSL3, and MOF proteins involved in dosage compensation also revealed no differences in the staining pattern between the X chromosome and the autosomes in both Sciara males and females. These results lead us to propose that different proteins in Drosophila and Sciara would implement dosage compensation.

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44

Ahmad, Kami, and Kent G. Golic. "Telomere Loss in Somatic Cells of Drosophila Causes Cell Cycle Arrest and Apoptosis." Genetics 151, no. 3 (March 1, 1999): 1041–51. http://dx.doi.org/10.1093/genetics/151.3.1041.

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Abstract Checkpoint mechanisms that respond to DNA damage in the mitotic cell cycle are necessary to maintain the fidelity of chromosome transmission. These mechanisms must be able to distinguish the normal telomeres of linear chromosomes from double-strand break damage. However, on several occasions, Drosophila chromosomes that lack their normal telomeric DNA have been recovered, raising the issue of whether Drosophila is able to distinguish telomeric termini from nontelomeric breaks. We used site-specific recombination on a dispensable chromosome to induce the formation of a dicentric chromosome and an acentric, telomere-bearing, chromosome fragment in somatic cells of Drosophila melanogaster. The acentric fragment is lost when cells divide and the dicentric breaks, transmitting a chromosome that has lost a telomere to each daughter cell. In the eye imaginal disc, cells with a newly broken chromosome initially experience mitotic arrest and then undergo apoptosis when cells are induced to divide as the eye differentiates. Therefore, Drosophila cells can detect and respond to a single broken chromosome. It follows that transmissible chromosomes lacking normal telomeric DNA nonetheless must possess functional telomeres. We conclude that Drosophila telomeres can be established and maintained by a mechanism that does not rely on the terminal DNA sequence.

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45

Somma, Maria Patrizia, Barbara Fasulo, Giorgia Siriaco, and Giovanni Cenci. "Chromosome Condensation Defects in barren RNA-Interfered Drosophila Cells." Genetics 165, no. 3 (November 1, 2003): 1607–11. http://dx.doi.org/10.1093/genetics/165.3.1607.

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Abstract Barren, the Drosophila homolog of XCAP-H, is one of three non-SMC subunits of condensin, a conserved 13S multiprotein complex required for chromosome condensation. Mutations in barren (barr) were originally shown to affect sister-chromatid separation during mitosis 16 of the Drosophila embryo, whereas condensation defects were not detected. In contrast, mutations in yeast homologs of barren result in defective mitotic chromosome condensation as well as irregular chromatid separation. We have used double-stranded RNA-mediated interference (RNAi) to deplete Barren in Drosophila S2 cells. Our analyses indicate that inactivation of barr leads to extensive chromosome condensation and disrupts chromatid segregation.

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46

Sawamura, K., M. T. Yamamoto, and T. K. Watanabe. "Hybrid lethal systems in the Drosophila melanogaster species complex. II. The Zygotic hybrid rescue (Zhr) gene of D. melanogaster." Genetics 133, no. 2 (February 1, 1993): 307–13. http://dx.doi.org/10.1093/genetics/133.2.307.

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Abstract Hybrid females from Drosophila simulans females x Drosophila melanogaster males die as embryos while hybrid males from the reciprocal cross die as larvae. We have recovered a mutation in melanogaster that rescues the former hybrid females. It was located on the X chromosome at a position close to the centromere, and it was a zygotically acting gene, in contrast with mhr (maternal hybrid rescue) in simulans that rescues the same hybrids maternally. We named it Zhr (Zygotic hybrid rescue). The gene also rescues hybrid females from embryonic lethals in crosses of Drosophila mauritiana females x D. melanogaster males and of Drosophila sechellia females x D. melanogaster males. Independence of the hybrid embryonic lethality and the hybrid larval lethality suggested in a companion study was confirmed by employing two rescue genes, Zhr and Hmr (Hybrid male rescue), in doubly lethal hybrids. A model is proposed to explain the genetic mechanisms of hybrid lethalities as well as the evolutionary pathways.

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47

Begun, David J., та Penn Whitley. "Adaptive Evolution of Relish, a Drosophila NF-κB/IκB Protein". Genetics 154, № 3 (1 березня 2000): 1231–38. http://dx.doi.org/10.1093/genetics/154.3.1231.

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Abstract NF-κB and IκB proteins have central roles in regulation of inflammation and innate immunity in mammals. Homologues of these proteins also play an important role in regulation of the Drosophila immune response. Here we present a molecular population genetic analysis of Relish, a Drosophila NF-κB/IκB protein, in Drosophila simulans and D. melanogaster. We find strong evidence for adaptive protein evolution in D. simulans, but not in D. melanogaster. The adaptive evolution appears to be restricted to the IκB domain. A possible explanation for these results is that Relish is a site of evolutionary conflict between flies and their microbial pathogens.

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48

Penalva, Luiz O. F., Hiroshi Sakamoto, Aurea Navarro-Sabaté, Eiji Sakashita, Begoña Granadino, Carmen Segarra, and Lucas Sánchez. "Regulation of the Gene Sex-lethal: A Comparative Analysis of Drosophila melanogaster and Drosophila subobscura." Genetics 144, no. 4 (December 1, 1996): 1653–64. http://dx.doi.org/10.1093/genetics/144.4.1653.

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The Drosophila gene Sex-lethal (Sxl) controls the processes of sex determination and dosage compensation. A Drosophila subobscura genomic fragment containing all the exons and the late and early promotors in the Sxl gene of D. melanogaster was isolated. Early Sxl expression in D. subobscura seems to be controlled at the transcriptional level, possibly by the X:A signal. In the region upstream of the early Sxl transcription initiation site are two conserved regions suggested to be involved in the early activation of Sxl. Late Sxl expression in D. subobscura produces four transcripts in adult females and males. In males, the transcripts have an additional exon which contains three translational stop codons so that a truncated, presumably nonfunctional Sxl protein is produced. The Sxl pre-mRNA of D. subobscura lacks the poly-U sequence presented at the polypirimidine tract of the 3′ splice site of the male-specific exon present in D. melanogaster. Introns 2 and 3 contain the Sxl-binding poly-U stretches, whose localization in intron 2 varies but in intron 3 is conserved. The Sxl protein is fully conserved at the amino acid level in both species.

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49

Aguadé, M., N. Miyashita, and C. H. Langley. "Polymorphism and divergence in the Mst26A male accessory gland gene region in Drosophila." Genetics 132, no. 3 (November 1, 1992): 755–70. http://dx.doi.org/10.1093/genetics/132.3.755.

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Abstract Drosophila males, like males of most other insects, transfer a group of specific proteins to the females during mating. These proteins are produced primarily in the accessory gland and are likely to influence the female's reproduction. The results of studies of DNA sequence polymorphism and divergence in two genes coding for male accessory gland proteins of Drosophila are reported here. The Mst26Aa and Mst26Ab transcription units are tandemly arranged in a approximately 1.6-kb segment in Drosophila sechellia, Drosophila mauritiana and Drosophila simulans as they were reported to be in Drosophila melanogaster. The DNA sequences of 10 alleles from D. melanogaster and one allele each from the three sibling species reveals a high degree of amino acid replacement variation. A substantial part of the variation is due to insertion/deletion differences. Possible functional significance of these amino acid sequence changes is discussed. Statistical analyses based on the neutral theory of molecular evolution show that the distribution of polymorphism over the 1.6-kb region is inconsistent with the pattern of divergence between the species. The amount of 4-cutter restriction map polymorphism in a larger sample of 75 alleles from the same D. melanogaster population is similar to that obtained from the DNA sequence of the 10 alleles (a pairwise average of 0.007 difference per site). The 6-cutter restriction map survey of a 18-kb region containing the Mst26A genes indicates that polymorphism in the region flanking these genes maybe higher. The failure of polymorphisms and divergence in the Mst26A region to conform to the expectations of a simple mutation-drift-equilibrium model indicates that selection in or near this region has played a role in the history of these genes.

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50

Kliman, R. M., and J. Hey. "DNA sequence variation at the period locus within and among species of the Drosophila melanogaster complex." Genetics 133, no. 2 (February 1, 1993): 375–87. http://dx.doi.org/10.1093/genetics/133.2.375.

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Abstract A 1.9-kilobase region of the period locus was sequenced in six individuals of Drosophila melanogaster and from six individuals of each of three sibling species: Drosophila simulans, Drosophila sechellia and Drosophila mauritiana. Extensive genealogical analysis of 174 polymorphic sites reveals a complex history. It appears that D. simulans, as a large population still segregating very old lineages, gave rise to the island species D. mauritiana and D. sechellia. Rather than considering these speciation events as having produced "sister" taxa, it seems more appropriate to consider D. simulans a parent species to D. sechellia and D. mauritiana. The order, in time, of these two phylogenetic events remains unclear. D. mauritiana supports a large number of polymorphisms, many of which are shared with D. simulans, and so appears to have begun and persisted as a large population. In contrast, D. sechellia has very little variation and seems to have experienced a severe population bottleneck. Alternatively, the low variation in D. sechellia could be due to recent directional selection and genetic hitchhiking at or near the per locus.

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