Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| nucleotide sequence of the xdh region in drosophila pseudoobscura and an analysis of the evolution of synonymous codons. | the nucleotide sequence of the xdh region of drosophila pseudoobscura is presented. the xdh gene structure and organization are compared with the homologous region in d. melanogaster. this locus is shown to have similar organization in the two species, although an additional intron and three insertion/deletion events are described for the d. pseudoobscura coding region. the encoded proteins are predicted to have very similar charges and hydrophobic/hydrophilic domains even though 11% of the amin ... | 1989 | 2493563 |
| cloning of the esterase-5 locus from drosophila pseudoobscura and comparison with its homologue in d. melanogaster. | a clone of the esterase-5 (est-5) gene from drosophila pseudoobscura has been isolated by hybridization to the cloned est-6 gene of d. melanogaster. southern analysis and sequencing of the cloned dna revealed three regions of similarity to est-6 that have been tentatively identified as genes, est-5a, est-5b, and est-5c. introduction of each of the three genes separately into d. melanogaster by p-element transformation has demonstrated that est-5b encodes an enzyme with the same physical properti ... | 1990 | 2178209 |
| developmental isolation and subsequent adult behavior of drosophila pseudoobscura. | when isolated from all contact with other flies until the opportunity to exercise mating choices, drosophila pseudoobscura displays genetically-mediated compensatory behavior: heterokaryotypic females are more vulnerable than homokaryotes to wholly restricted contact with conspecifics. they are less able to demonstrate normal frequency-dependent sexual selection after isolation than their own homokaryotypes. however, the later the isolation in this holometabolous insect--eggs, first instars, sec ... | 1990 | 2288548 |
| molecular analysis of the bicoid gene from drosophila pseudoobscura: identification of conserved domains within coding and noncoding regions of the bicoid mrna. | the specification of anterior positional information during drosophila embryogenesis is largely dependent upon the function of the maternal-effect gene bicoid (bcd). two aspects of bcd function are particularly striking. first, the bcd protein product forms a gradient during early embryogenesis, which regulates the transcription of at least one zygotic segmentation gene, hunchback, in a concentration dependent manner. secondly, formation of the bcd protein gradient is dependent upon the specific ... | 1990 | 1975239 |
| molecular analysis of evolutionary changes in the expression of drosophila esterases. | drosophila melanogaster transformed with the esterase 5 (est-5) gene from drosophila pseudoobscura were used to assess the evolutionary basis for differences in the sex- and tissue-specific expression of the esterase 5 (est 5) enzyme in d. pseudoobscura relative to its homologue in d. melanogaster, est 6. est 5 is expressed in the eyes and hemolymph of transformed d. melanogaster just as it is in d. pseudoobscura, but it is not detectable in the ejaculatory duct, where the homologous enzyme, est ... | 1990 | 1700427 |
| dna sequence evolution of the amylase multigene family in drosophila pseudoobscura. | the alpha-amylase locus in drosophila pseudoobscura is a multigene family of one, two or three copies on the third chromosome. the nucleotide sequences of the three amylase genes from a single chromosome of d. pseudoobscura are presented. the three amylase genes differ at about 0.5% of their nucleotides. each gene has a putative intron of 71 (amy1) or 81 (amy2 and amy3) bp. in contrast, drosophila melanogaster amylase genes do not have an intron. the functional amy1 gene of d. pseudoobscura diff ... | 1990 | 1699840 |
| mitochondrial dna evolution in the obscura species subgroup of drosophila. | mitochondrial dna (mtdna) restriction site maps for nine species of the drosophila obscura subgroup and for drosophila melanogaster were established. taking into account all restriction enzymes (12) and strains (45) analyzed, a total of 105 different sites were detected, which corresponds to a sample of 3.49% of the mtdna genome. based on nucleotide divergences, two phylogenetic trees were constructed assuming either constant or variable rates of evolution. both methods led to the same relations ... | 1990 | 2120450 |
| amylase gene expression in intraspecific and interspecific somatic transformants of drosophila. | the amylase locus in drosophila melanogaster normally contains two copies of the structural gene for alpha-amylase, a centromere-proximal copy, amy-p, and a distal copy, amy-d. products of the two genes may display discrete electrophoretic mobilities, but many strains known to carry the amy duplication are characterized by a single amylase electromorph, e.g., oregon-r, which produces the mobility variant amy-1. a transient expression assay was used in somatic transformation experiments to test t ... | 1990 | 1699842 |
| p-transposable vectors expressing a constitutive and thermoinducible hsp82-neo fusion gene for drosophila germline transformation and tissue-culture transfection. | three p-transposable vectors (approx. 16, 12, and 9 kb) were constructed containing a hsp82-neo fusion gene encoding a truncated heat-shock protein 82 of drosophila pseudoobscura and the bacterial neomycin phosphotransferase (npt). in transgenic drosophila melanogaster, hsp82-neo exhibits high levels of housekeeping gene promoter and npt activities in all cells in the absence of heat-shock and is further induced (fivefold) by elevated temperatures (35 degrees-36 degrees c). the hsp82-neo selecti ... | 1990 | 2165019 |
| conservatism of sites of trna loci among the linkage groups of several drosophila species. | the sites of seven trna genes (arg-2, lys-2, ser-2b, ser-7, thr-3, thr-4, val-3b) were studied by in situ hybridization. 125i-labeled trna probes from drosophila melanogaster were hybridized to spreads of polytene chromosomes prepared from four drosophila species representing different evolutionary lineages (d. melanogaster, drosophila hydei, drosophila pseudoobscura, and drosophila virilis). most trna loci occurred on homologous chromosomal elements of all four species. in some cases the number ... | 1990 | 2107332 |
| the effects of anthranilic acid on gene expression. | 1. a drosophila pseudoobscura amylase gene cloned in escherichia coli is expressed at high levels. the expression of this gene is repressed when glucose (0.5% final concentration) is added to a starch minimal medium culture of e. coli cells containing the amylase plasmid. 2. addition of anthranilic acid (5 and 7 mm final exogenous concentration) to catabolite repressed cells mimics the action of adenosine 3'5' cyclic monophosphate (camp) by depressing the expression of the amylase. 3. the result ... | 1990 | 1691993 |
| is there selection on rflp differences in mitochondrial dna? | experimental populations of drosophila simulans were established for the purpose of detecting the presence or absence of selection on a restriction fragment length polymorphism in mitochondrial dna (mtdna). it was then discovered that the founding strains differed with respect to the rickettsia-mediated incompatibility system in this species, which is maternally transmitted together with the mtdna differences. a population model was constructed using the known fitness effects of the incompatibil ... | 1990 | 1974225 |
| nucleotide sequence analysis of adh genes estimates the time of geographic isolation of the bogota population of drosophila pseudoobscura. | the population of drosophila pseudoobscura at bogota, columbia, is geographically and partially reproductively isolated from populations in the main body of the species in north america. the degree of genetic differentiation and time of divergence between populations at bogota and apple hill, ca, were estimated by comparison of 3388 nucleotides in the alcohol dehydrogenase region (adh and adh-dup genes) of 18 strains. of the 146 polymorphic nucleotide sites detected, 68 and 31 were unique to the ... | 1991 | 2068088 |
| four decades of inversion polymorphism in drosophila pseudoobscura. | we report data that continue the studies of dobzhansky and others on the frequencies of third-chromosome inversions in natural populations of drosophila pseudoobscura in north america. the common gene arrangements continue to be present in frequencies similar to those described four decades ago, and the broad geographic patterns also remain unchanged. there is only one pronounced trend over time: the increase in frequency of the tree line inversion in pacific coast populations. | 1991 | 1946458 |
| dosage compensation of the drosophila pseudoobscura hsp82 gene and the drosophila melanogaster adh gene at ectopic sites in d. melanogaster. | measurements were made of the amounts of larval rna transcribed from the autosomal adh gene of drosophila melanogaster and the x chromosomal hsp82 gene of drosophila pseudoobscura carried on the same p-element transposon inserted at various sites in the d. melanogaster genome. both genes were fully compensated at sites in euchromatic regions of the x chromosome but neither was compensated at a site in the centric beta-heterochromatin of the x chromosome. no compensation of the d. pseudoobscura h ... | 1991 | 1907376 |
| species differences in the temporal pattern of drosophila urate oxidase gene expression are attributed to trans-acting regulatory changes. | the drosophila melanogaster urate oxidase (uo)-encoding gene is expressed in the third-instar larva and adult. in contrast, the drosophila pseudoobscura uo gene is only expressed in the adult, whereas the drosophila virilis uo gene is expressed only in the third-instar larva. uo activity in these three drosophila species is detected exclusively within the malpighian tubules. by using p-element mediated germ-line transformation, uo genes from d. pseudoobscura and d. virilis were integrated into t ... | 1991 | 2062830 |
| interspecific comparisons of the structure and regulation of the drosophila ecdysone-inducible gene e74. | the drosophila melanogaster e74 gene is induced directly by the steroid hormone ecdysone and is a member of a small set of "early" genes that appear to trigger the onset of metamorphosis. the gene consists of three overlapping transcription units encoding two proteins, e74a and e74b, which possess a common c terminus. according to the ashburner model for ecdysone's action, an e74 protein product potentially functions as a transcriptional activator of "late" genes as well as a repressor of early ... | 1991 | 2016053 |
| length polymorphism in the threonine-glycine-encoding repeat region of the period gene in drosophila. | single-fly polymerase chain reaction amplification and direct dna sequencing revealed high levels of length polymorphism in the threonine-glycine encoding repeat region of the period (per) gene in natural populations of drosophila melanogaster. dna comparison of two alleles of identical lengths gave a high number of synonymous substitutions suggesting an ancient time of separation. however detailed examination of the sequences of different thr-gly length variants indicated that this divergence c ... | 1991 | 1904500 |
| the adh genomic region of drosophila ambigua: evolutionary trends in different species. | the study of individual genes is essential to a comprehensive understanding of genome evolution. the wealth of information on alcohol dehydrogenase (adh) in drosophila makes this gene particularly suitable for such analysis. we have characterized more than 4 kb of the genomic adh region in drosophila ambigua and compared this region to drosophila mauritiana and drosophila pseudoobscura. the presence of two genes, adh and 3'orf (open reading frame), has been confirmed and some of their essential ... | 1991 | 1908016 |
| perturbation-reperturbation test of selection vs. hitchhiking of the two major alleles of esterase-5 in drosophila pseudoobscura. | a perturbation-reperturbation tests selective neutrality of 100/100/100/100/100 and 106/100/100/100/100, the two most common alleles at the highly polymorphic x-linked locus esterase-5 in drosophila pseudoobscura. a total of 22 replicate populations are set up in cages, 11 start at a high frequency of 76% (u) and 11 at a low frequency of 21% (n) of the 106 allele. allele frequencies change directionally and decrease in both u and n populations as groups and reach equilibria of 60 and 14%, respec ... | 1991 | 1936955 |
| male-sex-ratio trait in drosophila pseudoobscura: frequency of autosomal aneuploid sperm. | males with the sr x chromosome show the "sex-ratio" (sr) phenotype in which they produce almost entirely daughters. the few sons (about 1%) are invariably sterile x/o males and result entirely from nullo-xy sperm. the "male-sex-ratio" (msr) phenotype is a modified form of sr in which sr/y males produce a higher frequency of sterile x/o sons. the msr trait is due to the presence of the sr x-chromosome in males which are also homozygous for one or more autosomes from the l116 strain. here the freq ... | 1991 | 2004709 |
| molecular evolution of inversions in drosophila pseudoobscura: the amylase gene region. | the amylase region of the third chromosome of drosophila pseudoobscura has been cloned and localized to cytological band 73a. it is contained within a series of highly polymorphic inversions and serves as a convenient tool for a molecular evolutionary analysis of the inverted gene arrangements. amylase in d. pseudoobscura is a family of three genes, and some chromosomes have deletions for one or two of them. two overlapping clones covering 26 kilobases were isolated and used as probes to survey ... | 1991 | 1702542 |
| estimates of gene flow in drosophila pseudoobscura determined from nucleotide sequence analysis of the alcohol dehydrogenase region. | the genetic structure of drosophila pseudoobscura populations was inferred from a nucleotide sequence analysis of a 3.4-kb segment of the alcohol dehydrogenase (adh) region. a total of 99 isochromosomal strains collected from 13 populations in north and south america were used to determine if any population departed from a neutral model and to estimate levels of gene flow between populations. this study also included the nucleotide sequences from two sibling species, d. persimilis and d. miranda ... | 1992 | 1427038 |
| molecular population genetics of an electrophoretically monomorphic protein in the alcohol dehydrogenase region of drosophila pseudoobscura. | nucleotide sequence data from the alcohol dehydrogenase (adh) region of 18 isochromosomal strains of drosophila pseudoobscura were used to determine whether the lack of amino acid polymorphism in adh results from a low neutral mutation rate or a recent directional selection event. we estimated the neutral mutation parameter, 4nmu, in synonymous sites for 17 subregions of adh. the nucleotide diversity data were tested for departures from an equilibrium neutral model with two statistical tests. th ... | 1992 | 1398051 |
| an evolutionary model for the duplication and divergence of esterase genes in drosophila. | the esterase 5 (est-5 = gene, est 5 = protein) enzyme in drosophila pseudoobscura is encoded by one of three paralogous genes, est-5a, est-5b, and est-5c, that are tightly clustered on the right arm of the x chromosome. the homologous est-6 locus in drosophila melanogaster has only one paralogous neighbor, est-p. comparisons of coding and flanking dna sequences among the three d. pseudoobscura and two d. melanogaster genes suggest that two paralogous genes were present before the divergence of d ... | 1992 | 1593643 |
| the urate oxidase gene of drosophila pseudoobscura and drosophila melanogaster: evolutionary changes of sequence and regulation. | the urate oxidase (uo) transcription unit of drosophila pseudoobscura was cloned, sequenced, and compared to the uo transcription unit from drosophila melanogaster. in both species the uo coding region is divided into two exons of approximately equal size. the deduced d. pseudoobscura and d. melanogaster uo peptides have 346 and 352 amino acid residues, respectively. the nucleotide sequences of the d. pseudoobscura and d. melanogaster uo protein-coding regions are 82.2% identical whereas the ded ... | 1992 | 1556745 |
| temporal stability of third-chromosome inversion frequencies in drosophila persimilis and d. pseudoobscura. | 1992 | 28568997 | |
| nucleotide polymorphism at the xanthine dehydrogenase locus in drosophila pseudoobscura. | sequential polyacrylamide electrophoresis has revealed 20 allozymes of xanthine dehydrogenase (xdh) in drosophila pseudoobscura. dna sequence determination of seven isolates of the xdh locus that represent six allozyme classes are presented here. of the 5,456 sites examined, 180 are polymorphic, with 27 polymorphisms occurring at nonsynonymous, or replacement, sites. an average of nine amino acids differ between xdh allozyme classes, with 85% of the polymorphic amino acids singly represented. th ... | 1992 | 1552841 |
| founder-flush speciation in drosophila pseudoobscura: a large-scale experiment. | a founder-flush-crash model of speciation has been proposed that may particularly apply to island and other colonizations. previous laboratory experiments testing the model have given inconsistent results. we have conducted a large experiment with drosophila pseudoobscura designed to meet the essential postulates of the model and to separately test some of the postulates. forty-five experimental and 12 control populations have been studied during seven successive founder-flush-crash cycles, or a ... | 1993 | 28568735 |
| codon usage bias and base composition of nuclear genes in drosophila. | 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 ne ... | 1993 | 8349115 |
| the l(2)gl homologue of drosophila pseudoobscura suppresses tumorigenicity in transgenic drosophila melanogaster. | mutations in the tumour-suppressor gene lethal(2)giant larvae (l(2)gl) of drosophila cause malignant transformation of the optic centres of the larval brain and the imaginal discs. we report the cloning and sequencing of the l(2)gl gene from drosophila pseudoobscura. comparison of this sequence with d. melanogaster reveals a significant sequence conservation within the l(2)gl protein-coding domain and a strong sequence divergence in the 5' promoter region and in the introns. the deduced amino ac ... | 1993 | 8389031 |
| adenine phosphoribosyltransferase genes in two drosophila species: dosage compensation, a nuclear matrix attachment site, and a novel intron position. | the aprt locus of drosophila encodes the structural gene for the purine salvage enzyme adenine phosphoribosyltransferase. aprt is autosomal and enzyme activity is gene-dose-dependent in drosophila melanogaster. however, aprt is x-linked and dosage compensated in drosophila pseudoobscura, as shown here. the aprt genes of both drosophila species contain a dna sequence associated with nuclear matrix attachment sites and these aprt sequences specifically bind to nuclear matrix in vitro. putative pro ... | 1993 | 8492806 |
| nucleotide divergence of the rp49 gene region between drosophila melanogaster and two species of the obscura group of drosophila. | a 2.1-kb ssti fragment including the rp49 gene and the 3' end of the delta-serendipity gene has been cloned and sequenced in drosophila pseudoobscura. rp49 maps at region 62 on the tip of chromosome ii of this species. both the coding and flanking regions have been aligned and compared with those of d. subobscura. there is no evidence for heterogeneity in the rate of silent substitution between the rp49 coding region and the rate of substitutions in flanking regions, the overall silent divergenc ... | 1993 | 8483162 |
| structural changes in the antennapedia complex of drosophila pseudoobscura. | the discovery of the striking positional conservation between the antennapedia and bithorax homeotic gene complexes (ant-c and bx-c) in drosophila melanogaster and the murine hox and human hox clusters has had a substantial impact on our understanding of the evolution of development and its genetic regulation. structural differences do exist among the mammalian hox complexes and the ant-c in d. melanogaster. to gain further insight into the evolutionary changes among these complexes, the ant-c w ... | 1993 | 8099892 |
| estimates of linkage disequilibrium and the recombination parameter determined from segregating nucleotide sites in the alcohol dehydrogenase region of drosophila pseudoobscura. | the alcohol dehydrogenase (adh) region of drosophila pseudoobscura, which includes the two genes adh and adh-dup, was used to examine the pattern and organization of linkage disequilibrium among pairs of segregating nucleotide sites. a collection of 99 strains from the geographic range of d. pseudoobscura were nucleotide-sequenced with polymerase chain reaction-mediated techniques. all pairs of the 359 polymorphic sites in the 3.5-kb adh region were tested for significant linkage disequilibrium ... | 1993 | 8244013 |
| temperature related fertility selection on body size and the sex-ratio gene arrangement in drosophila pseudoobscura. | we measured temperature-dependent fertility selection on body size in drosophila pseudoobscura in the laboratory. one hundred single females of each of the three karyotypes involving the 'sex-ratio' (sr) and the standard (st) gene arrangement on the sex chromosome laid eggs at either 18 or 24 degrees c. the experiment addressed the following hypotheses: (a) fertility selection on body size is weaker at the higher temperature, explaining in part why genetically smaller flies appear to evolve in p ... | 1993 | 8405993 |
| the effect of periodic bottlenecks on the competitive ability of drosophila pseudoobscura lines. | competition experiments between several drosophila pseudoobscura strains that were previously subjected to periodic bottlenecks of different sizes and d. willistoni have been carried out. contrary to previous results with these two species, where stable coexistence was detected, populations of d. pseudoobscura displaced d. willistoni in a few generations. by using a relative fitness measure, the control lines (that had not gone through bottlenecks) outcompeted d. willistoni faster than bottlenec ... | 1993 | 8432660 |
| big flies, small repeats: the "thr-gly" region of the period gene in diptera. | the region of the clock gene period (per) that encodes a repetitive tract of threonine-glycine (thr-gly) pairs has been compared between dipteran species both within and outside the drosophilidae. all the non-drosophilidae sequences in this region are short and present a remarkably stable picture compared to the drosophilidae, in which the region is much larger and extremely variable, both in size and composition. the accelerated evolution in the repetitive region of the drosophilidae appears to ... | 1994 | 7815924 |
| the history of a genetic system. | although the chromosomal polymorphism for inversions in drosophila pseudoobscura is one of the best studied systems in population genetics, the identity of the ancestral gene arrangement has remained unresolved for more than 50 years. there are more than 40 gene arrangements, and 4 of them (standard, hypothetical, santa cruz, and tree line) have been considered as candidates for the ancestral type. we propose a framework of competing hypotheses to distinguish among the alternatives. two conclusi ... | 1994 | 7518922 |
| functional nonequivalence of sperm in drosophila pseudoobscura. | we report on a form of sperm polymorphism, termed polymegaly, that occurs in species of the drosophila obscura group. individual males of species in this group characteristically produce more than one discrete length of nucleated, motile sperm. hypotheses suggested to explain the evolutionary significance of sperm polymorphism have been either nonadaptive or adaptive, with the latter focusing on sperm competition or nutrient provisioning. these hypotheses assume all sperm types fertilize eggs; h ... | 1994 | 7972038 |
| interspecific transgenic analysis of basal versus heat-shock-induced expression of a drosophila pseudoobscura hsp82-neo fusion gene in d. melanogaster. | drosophila melanogaster transformants containing a d. pseudoobscura hsp82-neo fusion gene were used to examine the relationship between chromosome structure and its variation to transcriptional activation and gene expression. at normal temperatures (25° c) transgenic hsp82-neo was transcribed in diffuse polytene chromosomal bands encoding antibiotic g418-resistance without intensive puff formation. substantial basal expression of the transgene was observed in all tissues examined: salivary gland ... | 1994 | 28305933 |
| components acting in localization of bicoid mrna are conserved among drosophila species. | substantial insights into basic strategies for embryonic body patterning have been obtained from genetic analyses of drosophila melanogaster. this knowledge has been used in evolutionary comparisons to ask if genes and functions are conserved. to begin to ask how highly conserved are the mechanisms of mrna localization, a process crucial to drosophila body patterning, we have focused on the localization of bcd mrna to the anterior pole of the embryo. here we consider two components involved in t ... | 1994 | 8070663 |
| synonymous codon usage in drosophila melanogaster: natural selection and translational accuracy. | i present evidence that natural selection biases synonymous codon usage to enhance the accuracy of protein synthesis in drosophila melanogaster. since the fitness cost of a translational misincorporation will depend on how the amino acid substitution affects protein function, selection for translational accuracy predicts an association between codon usage in dna and functional constraint at the protein level. the frequency of preferred codons is significantly higher at codons conserved for amino ... | 1994 | 8005445 |
| evolutionary conservation of the structure and expression of alternatively spliced ultrabithorax isoforms from drosophila. | in drosophila melanogaster, alternatively spliced mrnas from the homeotic gene ultrabithorax (ubx) encode a family of structurally distinct homeoprotein isoforms. the developmentally regulated expression patterns of these isoforms suggest that they have specialized stage- and tissue-specific functions. to evaluate the functional importance of ubx isoform diversity and gain clues to the mechanism that regulates processing of ubx rnas, we have investigated whether the ubx rnas of other insects und ... | 1994 | 7911773 |
| evidence for gene conversion in the amylase multigene family of drosophila pseudoobscura. | the alpha-amylase (amy) multigene family in drosophila pseudoobscura is located on the third chromosome, which is polymorphic for more than 40 inverted gene arrangements. the number of copies in this family ranges from one to three, depending on the arrangement in question. a previous study of the three amy genes from the standard (st) arrangement suggested either that duplicated copies (amy2 and amy3) are functionally constrained or that they are undergoing gene conversion with amy1. in order t ... | 1995 | 7659012 |
| separate cis-regulatory sequences control expression of serendipity beta and janus a, two immediately adjacent drosophila genes. | the genes janus (jan) a and b, and serendipity (sry) beta and delta are two pairs of duplicated genes that are adjacent to each other on the third chromosome of drosophila melanogaster. the jan a and sry beta genes are expressed throughout development in both males and females. they are transcribed in opposite orientations from start sites separated by only 173 bp of dna. we report here the complete sequence of the jan a and b genes in drosophila pseudoobscura, a species distantly related to d. ... | 1995 | 7700229 |
| p1 clones from drosophila melanogaster as markers to study the chromosomal evolution of muller's a element in two species of the obscura group of drosophila. | thirty p1 clones from the x chromosome (muller's a element) of drosophila melanogaster were cross-hybridized in situ to drosophila subobscura and drosophila pseudoobscura polytene chromosomes. an additional recombinant phage lambda dsuby was also used as a marker. twenty-three (77%) of the p1 clones gave positive hybridization on d. pseudoobscura chromosomes but only 16 (53%) did so with those of d. subobscura. eight p1 clones gave more than one hybridization signal on d. pseudoobscura and/or d. ... | 1995 | 8585990 |
| conservation and function of the transcriptional regulatory protein runt. | a phylogenetic approach was used to identify conserved regions of the transcriptional regulator runt. alignment of the deduced protein sequences from drosophila melanogaster, drosophila pseudoobscura, and drosophila virilis revealed eight blocks of high sequence homology separated by regions with little or no homology. the largest conserved block contains the runt domain, a dna and protein binding domain conserved in a small family of mammalian transcription factors. the functional properties of ... | 1995 | 7568078 |
| sequence and evolution of the drosophila pseudoobscura glycerol-3-phosphate dehydrogenase locus. | the gpdh genomic region has been cloned and sequenced in drosophila pseudoobscura. a total of 6.8 kb of sequence was obtained, encompassing all eight exons of the gene. the exons have been aligned with the sequence from d. melanogaster, and the rates of synonymous and nonsynonymous substitution have been compared to those of other genes sequenced in these two species. gpdh has the lowest rate of nonsynonymous substitution yet seen in genes sequenced in both d. pseudoobscura and d. melanogaster. ... | 1995 | 8587133 |
| maintenance of pre-mrna secondary structure by epistatic selection. | linkage disequilibrium between polymorphisms in a natural population may result from various evolutionary forces, including random genetic drift due to sampling of gametes during reproduction, restricted migration between subpopulations in a subdivided population, or epistatic selection. in this report, we present evidence that the majority of significant linkage disequilibria observed in introns of the alcohol dehydrogenase locus (adh) of drosophila pseudoobscura are due to epistatic selection ... | 1995 | 7568070 |
| molecular basis of polymorphism at the esterase-5b locus in drosophila pseudoobscura. | sequence variation was studied in a 2.2-kb region encompassing the esterase-5b locus in drosophila pseudoobscura from two california populations. in these populations, two common electrophoretic classes and many less frequent variants occur, and it was formerly shown by keith (1983) that allele frequencies differed from random distribution under an infinite allele model. nucleotide polymorphisms were determined in 16 sequences representing 14 electrophoretic classes. there was no significant seq ... | 1995 | 8536974 |
| interchromosomal exchange of genetic information between gene arrangements on the third chromosome of drosophila pseudoobscura. | during the last 60 years, the inversion polymorphism on the third chromosome of drosophila pseudoobscura has become a case study of the evolution of linked blocks of genes, isolated from each other by the suppression of recombination in heterozygotes for different inversions. due to its location within inverted regions in most gene arrangements, the amylase (amy) gene region can be used to elucidate the molecular pattern of evolution in these inversions. we studied this region in the tree line p ... | 1995 | 7476140 |
| speciation driven by natural selection in drosophila. | reinforcement is the process by which natural selection strengthens sexual isolation between incipient species, reducing the frequency of maladaptive hybridization and hence completing reproductive isolation. although this model of speciation was once widely accepted, its plausibility and experimental support have been recently attacked. here we provide an example of speciation by reinforcement, in the north american fruitfly drosophila pseudoobscura. the results suggest that females of d. pseud ... | 1995 | 7791899 |
| competition between mitochondrial haplotypes in distinct nuclear genetic environments: drosophila pseudoobscura vs. d. persimilis. | a test for coadaptation of nuclear and mitochondrial genomes was performed using the sibling species, drosophila pseudoobscura and d. persimilis. two lines of flies with "disrupted" cytonuclear genotypes were constructed by repeated backcrossing of males from one species to females carrying mitochondrial dna (mtdna) from the other species. each "disrupted" strain was competed in population cages with the original stock of each species from which the recurrent males were obtained during the backc ... | 1995 | 7498735 |
| founder-effect speciation theory: failure of experimental corroboration. | the theory of founder-effect speciation proposes that colonization by very few individuals of an empty habitat favors rapid genetic changes and the evolution of a new species. we report here the results obtained in a 10-year-long and large-scale experiment with drosophila pseudoobscura designed to test the theory. in our experimental protocol, populations are established with variable numbers of very few individuals and allowed to expand greatly for several generations until conditions of severe ... | 1995 | 7732017 |
| the speciation history of drosophila pseudoobscura and close relatives: inferences from dna sequence variation at the period locus. | thirty-five period locus sequences from drosophila pseudoobscura and its siblings species, d. p. bogotana, d. persimilis, and d. miranda, were studied. a large amount of variation was found within d. pseudoobscura and d. persimilis, consistent with histories of large effective population sizes. d. p. bogotana, however, has a severe reduction in diversity. combined analysis of per with two other loci, in both d. p. bogotana and d. pseudoobscura, strongly suggest this reduction is due to recent di ... | 1996 | 8913754 |
| genetics of a difference in cuticular hydrocarbons between drosophila pseudoobscura and d. persimilis. | we identify a fixed species difference in the relative concentrations of the cuticular hydrocarbons 2-methyl hexacosane and 5,9-pentacosadiene in drosophila pseudoobscura and d. persimilis, and determine its genetic basis. in backcross males, this difference is due to genes on both the x and second chromosomes, while the other two major chromosomes have no effect. in backcross females, only the second chromosome has a significant effect on hydrocarbon phenotype, but dominant genes on the x chrom ... | 1996 | 8940900 |
| the evolutionary history of the amylase multigene family in drosophila pseudoobscura. | in drosophila pseudoobscura, the amylase (amy) multigene family is contained within a series of inversions, or gene arrangements, on the third chromosome. the standard (st), santa cruz (sc), and tree line (tl) inversions are central to the phylogeny of arrangements, and have clusters of other arrangements derived from them. the gene arrangements belonging to each of these three clusters have a characteristic number of amy genes, ranging from three in st to two in sc to one in tl. this distributi ... | 1996 | 8754223 |
| relative effects of female fecundity and male mating success on fertility selection in drosophila pseudoobscura. | the fertility component of natural selection acting on chromosomal inversions in two experimental populations of drosophila pseudoobscura was subdivided into the effects of female fecundity and male mating success. the offspring of the three female genotypes could be distinguished by their mitochondrial dna haplotypes, thus permitting a direct measurement of the relative fecundities of the female genotype. the effects of male mating success on inversion frequency were measured by comparing inver ... | 1996 | 8610171 |
| molecular evolution of the sex-ratio inversion complex in drosophila pseudoobscura: analysis of the esterase-5 gene region. | the sex-ratio chromosome in drosophila pseudoobscura is subject to meiotic drive. it is associated with a series of three nonoverlapping paracentric inversions on the right arm of the x chromosome. the esterase-5 gene region has been localized to section 23 within the subbasal inversion of the sex-ratio inversion complex, making esterase-5 a convenient locus for molecular evolutionary analyses of the sex-ratio inversion complex and the associated drive system. a 504-bp fragment of noncoding, int ... | 1996 | 8587496 |
| cytoplasmic incompatibility and mating preference in colombian drosophila pseudoobscura. | macrae and anderson observed a large frequency change of mitochondrial dna (mtdna) haplotypes in a population initiated with two allopatric strains of drosophila pseudoobscura, boger from colombia and ah162 from california. they concluded that mtdna haplotypes in d. pseudoobscura are not always selectively neutral. nigro and prout suggested, however, that a maternally transmitted incompatibility system, similar to the one they observed in two strains of d. simulans from italy, could account for ... | 1996 | 8770596 |
| mitochondrial gene divergence of colombian drosophila pseudoobscura. | isolated populations of drosophila pseudoobscura, separated from north american populations by about 2,400 km, were found in colombia in 1960. we compared for sequences of the small ribosomal rna (srrna) gene on the mitochondria between north american and colombian d. pseudoobscura in order to clarify the age of the colombian isolates. the north american populations were not genetically different from each other but were genetically different from the colombian populations. the mexican strains r ... | 1996 | 8896379 |
| the 5' regulatory region from the drosophila pseudoobscura hsp82 gene results in a high level of reporter gene expression in lucilia cuprina embryos. | we have previously examined the efficiency of two drosophila melanogaster promoters to enable reporter gene expression in embryos of the australian sheep blowfly, lucilia cuprina. both the hsp70 heat-shock promoter and the actin5c promoter resulted in low levels of expression of a reporter gene in these embryos. in this study, the d. pseudoobscura hsp82 promoter (phsp82) was tested for its ability to direct the expression of the escherichia coli chloramphenicol acetyltransferase-encoding gene (c ... | 1996 | 8917099 |
| postmating isolation analysis in founder-flush experimental populations of drosophila pseudoobscura. | 1996 | 28568951 | |
| selection and the "sex-ratio" polymorphism in natural populations of drosophila pseudoobscura. | "sex-ratio" (sr) is a naturally occurring x-linked meiotic drive system, where the sr-x chromosome is transmitted to nearly all progeny of sr males. it occurs at frequencies of up to 25% in some populations of drosophila pseudoobscura. because of the twofold drive advantage, sr should rapidly fix in populations, causing the extinction of the species, unless opposed by strong selection. i examine several of the adult components of fitness, including the frequencies of all genotypic mating combina ... | 1996 | 28568936 |
| genetics of sexual isolation and courtship dysfunction in male hybrids of drosophila pseudoobscura and drosophila persimilis. | despite the importance of sexual isolation to speciation, few studies have analyzed the genetic basis of interspecific mating discrimination, particularly using hybrid males. in this study, i investigated the genetic basis of sexual isolation using male hybrids of drosophila pseudoobscura and d. persimilis. hybrid male mating success was caused by interactions between the x-chromosome and autosomes (or y-chromosome), and different arms of the x-chromosome contributed to mating success with femal ... | 1997 | 28568570 |
| divergent and conserved features in the spatial expression of the drosophila pseudoobscura esterase-5b gene and the esterase-6 gene of drosophila melanogaster. | the regulatory regions of homologous genes encoding esterase 6 (est-6) of drosophila melanogaster and esterase 5b (est-5b) of drosophila pseudoobscura show very little similarity. we have undertaken a comparative study of the pattern of expression directed by the est-5b and est-6 5'-flanking dna to attempt to reveal conserved elements regulating tissue-specific expression in adults. esterase regulatory sequences were linked to a lacz reporter gene and transformed into d. melanogaster embryos. es ... | 1997 | 9223257 |
| gene flow and natural selection in the origin of drosophila pseudoobscura and close relatives. | the divergence of drosophila pseudoobscura and close relatives d. persimilis and d. pseudoobscura bogotana has been studied using comparative dna sequence data from multiple nuclear loci. new data from the hsp82 and adh regions, in conjunction with existing data from adh and the period locus, are examined in the light of various models of speciation. the principal finding is that the three loci present very different histories, with adh indicating large amounts of recent gene flow among the taxa ... | 1997 | 9383055 |
| a demographic approach to selection. | the concepts of demography provide a means of combining the ecological approach to population growth with the genetical approach to natural selection. we have utilized the demographic theory of natural selection developed by norton and charlesworth to analyze life history schedules of births and deaths for populations of genotypes in drosophila pseudoobscura. our populations illustrate a stable genetic equilibrium, an unstable genetic equilibrium, and a case of no equilibrium. we have estimated ... | 1997 | 9223258 |
| on the mode of gene-dosage compensation in drosophila. | a procedure is described for determining the mode and magnitude of gene-dosage compensation of transformed genes. it involves measurement of the ratio of the activity of a gene inserted at x-linked sites to the activity of the same gene inserted at autosomal sites. applying the procedure to the drosophila pseudoobscura hsp82 gene inserted at ectopic sites in d. melanogaster and taking gene activity as proportional to the amount of transcript per gene copy, we conclude that (1) in both adults and ... | 1997 | 9055082 |
| courtship songs of drosophila pseudoobscura and d. persimilis: analysis of variation. | differences in drosophila courtship song elements are thought to confer species sexual isolation because of the low levels of variation within species, the large differences often seen between closely related species, and the results of experiments using synthetic songs in two species groups. in this study, we reanalyse the courtship song elements of d. pseudoobscura and d. persimilis. we confirmed the differences between these species in high-rate repetition song interpulse interval (ipi) and i ... | 1998 | 9710468 |
| mutation and selection at silent and replacement sites in the evolution of animal mitochondrial dna. | two patterns are presented that illustrate the interaction of mutation and selection in the evolution of animal mtdna: 1) variation among taxa in the ratio of polymorphism to divergence (rpd) at silent and replacement sites in protein-coding genes, and 2) strand-differences in polymorphism and divergence at 'silent' sites that suggest a mutation-selection balance in the evolution of codon usage. cytochrome b data from genbank show that about half of the species pairs tested have a significant ex ... | 1998 | 9720291 |
| the role of gene conversion in determining sequence variation and divergence in the est-5 gene family in drosophila pseudoobscura. | nucleotide sequences of eight est-5a and est-5c genes corresponding to previously sequenced est-5b genes in drosophila pseudoobscura were determined to compare patterns of polymorphism and divergence among members of this small gene family. the three esterase genes were also sequenced from d. persimilis and d. miranda for interspecific comparisons. the data provide evidence that gene conversion between loci contributes to polymorphism and to the homogenization of the est5 genes. for est-5b, whic ... | 1998 | 9475741 |
| conservation of read-through transcription of the drosophila serendipity genes during evolution is gratuitous. | the drosophila melanogaster serendipity (sry) genes sry alpha and sry beta, which code for unrelated proteins and functions, are transcribed both as monocistronic (sry alpha, srv beta) and dicistronic (sry beta-sry alpha) polyadenylated transcripts, the three types of transcripts being differentially expressed throughout development. we show here that, while the sry gene cluster is conserved in two other distantly related drosophila species, sry beta-sry alpha dicistronic transcription is observ ... | 1998 | 9790579 |
| sex-related genes, directional sexual selection, and speciation. | reproductive isolation and speciation can result from the establishment of either premating or postmating barriers that restrict gene flow between populations. recent studies of speciation have been dominated by a molecular approach to dissect the genetic basis of hybrid male sterility, a specific form of postmating reproductive isolation. however, relatively little attention has been paid to the evolution of genes involved in premating isolation and genes generally involved in other sex-related ... | 1998 | 9656489 |
| the correlation between synonymous and nonsynonymous substitutions in drosophila: mutation, selection or relaxed constraints? | codon usage bias, the preferential use of particular codons within each codon family, is characteristic of synonymous base composition in many species, including drosophila, yeast, and many bacteria. preferential usage of particular codons in these species is maintained by natural selection acting largely at the level of translation. in drosophila, as in bacteria, the rate of synonymous substitution per site is negatively correlated with the degree of codon usage bias, indicating stronger select ... | 1998 | 9755207 |
| molecular coevolution within a drosophila clock gene. | the period (per) gene in drosophila melanogaster provides an integral component of biological rhythmicity and encodes a protein that includes a repetitive threonine-glycine (thr-gly) tract. similar repeats are found in the frq and wc2 clock genes of neurospora crassa and in the mammalian per homologues, but their circadian functions are unknown. in drosophilids, the length of the thr-gly repeat varies widely between species, and sequence comparisons have suggested that the repeat length coevolve ... | 1998 | 9539762 |
| amyrel, a paralogous gene of the amylase gene family in drosophila melanogaster and the sophophora subgenus. | we describe a gene from drosophila melanogaster related to the alpha-amylase gene amy. this gene, which exists as a single copy, was named amyrel. it is strikingly divergent from amy because the amino acid divergence is 40%. the coding sequence is interrupted by a short intron at position 655, which is unusual in amylase genes. amyrel has also been cloned in drosophila ananassae, drosophila pseudoobscura, and drosophila subobscura and is likely to be present throughout the sophophora subgenus, b ... | 1998 | 9618501 |
| sperm production and sterility in hybrids between two subspecies of drosophila pseudoobscura. | subspecies of drosophila pseudoobscura, one occurring in the united states and the other in bogota, columbia, exhibit haldane's rule in one direction of the cross. additionally, d. pseudoobscura produces two sperm types: short, sterile sperm and long, fertile, sperm. here i examine the relationship between the production of short and long sperm and hybrid sterility. fertile and sterile hybrid males produce a greater proportion of short sperm compared to parental males with sterile hybrids produc ... | 1998 | 28568153 |
| interspecific laboratory competition of the recently sympatric species drosophila subobscura and drosophila pseudoobscura. | -drosophila subobscura and d. pseudoobscura are closely related species coexisting on the west coast of north america, which was recently colonized by d. subobscura. in competition experiments with overlapping generations, d. subobscura is eliminated by d. pseudoobscura in a few generations at all four temperatures and two initial frequencies tested. yet in one-species cultures, d. subobscura thrives at all experimental conditions. single-generation competition experiments reveal lower survivors ... | 1998 | 28568145 |
| different period gene repeats take 'turns' at fine-tuning the circadian clock. | the repetitive region of the circadian clock gene period in drosophila pseudoobscura consists predominantly of a pentapeptide sequence whose consensus is nsgad. in d. melanogaster, this region is replaced by a dipeptide thr-gly repeat, which plays a role in the thermal stability of the circadian phenotype. the thr-gly repeat has been shown to form a type ii or iii beta-turn, whose conformational monomer is (thr-gly)3. here we report, using conformational analyses, that both an nsgad pentapeptide ... | 1999 | 10629978 |
| dna sequence variation and the recombinational landscape in drosophila pseudoobscura: a study of the second chromosome. | the relationship between rates of recombination and dna sequence polymorphism was analyzed for the second chromosome of drosophila pseudoobscura. we constructed integrated genetic and physical maps of this chromosome using molecular markers at 10 loci spanning most of its physical length. the total length of the map was 128.2 cm, almost twice that of the homologous chromosome arm (3r) in d. melanogaster. there appears to be very little centromeric suppression of recombination, and rates of recom ... | 1999 | 10511563 |
| gene flow between drosophila pseudoobscura and d. persimilis. | 2000 | 11209795 | |
| analysis of a swallow homologue from drosophila pseudoobscura. | we analyzed a functional homologue of the swallow gene from drosophila pseudoobscura. the swallow gene of d. melanogaster plays an essential role in localizing bicoid mrna in oocytes, and swallow mutant embryos show anterior pattern defects that result from the lack of localization of the bicoid morphogen. the pseudoobscura homologue rescues the function of swallow mutants when introduced into the genome of d. melanogaster, and its expression is similar to that of the melanogaster gene. the pred ... | 2000 | 11180817 |
| molecular population genetics of x-linked genes in drosophila pseudoobscura. | this article presents a nucleotide sequence analysis of 500 bp determined in each of five x-linked genes, runt, sisterlessa, period, esterase 5, and heat-shock protein 83, in 40 drosophila pseudoobscura strains collected from two populations. estimates of the neutral migration parameter for the five loci show that gene flow among d. pseudoobscura populations is sufficient to homogenize inversion frequencies across the range of the species. nucleotide diversity at each locus fails to reject a neu ... | 2000 | 10978282 |
| a biogeographic genetic approach for testing the role of reinforcement: the case of drosophila pseudoobscura and d. persimilis. | the role of reinforcement in speciation can be explained by two distinct models. in model i, two diverged populations hybridize and produce fertile hybrids that successfully backcross (hybridization with gene flow). in model ii, two populations hybridize but succeeding backcrosses are unproductive (hybridization without gene flow). using drosophila persimilis and d. pseudoobscura, we have tested model i by comparing the extent of heterospecific introgression in sympatric versus allopatric popula ... | 2000 | 10937197 |
| high frequency of microsatellites in drosophila pseudoobscura. | using 30,000 bp of anonymous sequence data, we note that dinucleotide repeat arrays appear to be much more common in drosophila pseudoobscura than in d. melanogaster or d. simulans. repeat arrays bearing five or more units are situated on average once every 3000 bp in d. pseudoobscura, and repeat arrays bearing ten or more units are situated on average once every 7500 bp. we did not detect an association between microsatellite presence and gc-content of flanking regions. | 2000 | 10925790 |
| a re-evaluation of 12s ribosomal rna variability in drosophila pseudoobscura. | two recent studies have presented conflicting views on variation present within the 294 base third domain of the 12s rrna gene in the genus drosophila, and in d. pseudoobscura in particular. one study suggested that this gene is highly invariant across the genus, while another recovered 22 distinct haplotypes from 22 strains of d. pseudoobscura. we have sequenced this gene in numerous lines of d. pseudoobscura and its relatives, noting only two haplotypes in the third domain, and we failed to co ... | 2000 | 10833200 |
| microsatellite variation in populations of drosophila pseudoobscura and drosophila persimilis. | we have isolated, characterized and mapped 33 dinucleotide, three trinucleotide and one tetranucleotide repeat loci from the four major chromosomes of drosophila pseudoobscura. average inferred repeat unit length of the dinucleotide repeats is 12 repeat units, similar to d. melanogaster. assays of d. pseudoobscura and populations of its sibling species, d. persimilis, using 10 of these loci show extremely high levels of variation compared with similar studies of dinucleotide repeat variation in ... | 2000 | 10740918 |
| effects of temperature and temperature-steps on circadian locomotor rhythmicity in the blow fly calliphora vicina. | the free-running period (in darkness) of the locomotor activity rhythm in adult blow flies (calliphora vicina) was temperature-compensated between 15 and 25 degrees c, showing q(10) values between 0.98 and 1.04. single steps-up (20 to 25 degrees c) or steps-down (20 to 15 degrees c) in temperature caused stable phase shifts of the activity rhythm, giving rise to temperature-step phase response curves (prcs) with both advances and delays. phase advances, however, were dominant for steps-up, and p ... | 2000 | 12770234 |
| high density of long dinucleotide microsatellites in drosophila subobscura. | we isolated 96 dinucleotide repeats with five or more tandemly repeated units from a subgenomic drosophila subobscura library. the mean repeat unit length of microsatellite clones in d. subobscura is 15, higher than that observed in other drosophila species. population variation was assayed in 32-40 chromosomes from barcelona, spain, using 18 randomly chosen microsatellite loci. positive correlation between measures of variation and perfect repeat length measures (mean size, most common, and lon ... | 2000 | 10908646 |
| associations between female remating behavior, oogenesis and oviposition in drosophila melanogaster and drosophila pseudoobscura. | an association between female remating behavior, oogenesis and oviposition was examined in drosophila melanogaster and drosophila pseudoobscura to investigate mechanisms that elicit remating. females receptive to remating oviposited more eggs in both species; however, the species differed in the association between remating behavior and the number and distribution of oocyte stages. we found no differences in the number of either developing eggs of different stages or mature eggs between female d ... | 2000 | 10891578 |
| the genetics of reproductive isolation and the potential for gene exchange between drosophila pseudoobscura and d. persimilis via backcross hybrid males. | hybrid male sterility, hybrid inviability, sexual isolation, and a hybrid male courtship dysfunction reproductively isolate drosophila pseudoobscura and d. persimilis. previous studies of the genetic bases of these isolating mechanisms have yielded only limited information about how much and what areas of the genome are susceptible to interspecies introgression. we have examined the genetic basis of these barriers to gene exchange in several thousand backcross hybrid male progeny of these specie ... | 2001 | 11327159 |
| courtship songs of drosophila pseudoobscura and d. persimilis. ii. genetics of species differences. | although male courtship songs have been repeatedly implicated in sexual isolation between numerous drosophila species, no genetic studies have evaluated the genetic basis of differences between species beyond using quantitative genetic analyses of hybrids or surveying associations of song characters to five or fewer genetic markers. here, we dissect the genetic basis of the difference between d. pseudoobscura and d. persimilis in two courtship song elements (interpulse interval and intrapulse fr ... | 2001 | 11298817 |
| protein variation in adh and adh-related in drosophila pseudoobscura. linkage disequilibrium between single nucleotide polymorphisms and protein alleles. | a 3.5-kb segment of the alcohol dehydrogenase (adh) region that includes the adh and adh-related genes was sequenced in 139 drosophila pseudoobscura strains collected from 13 populations. the adh gene encodes four protein alleles and rejects a neutral model of protein evolution with the mcdonald-kreitman test, although the number of segregating synonymous sites is too high to conclude that adaptive selection has operated. the adh-related gene encodes 18 protein haplotypes and fails to reject an ... | 2001 | 11606543 |
| chromosomal inversions and the reproductive isolation of species. | recent genetic studies have suggested that many genes contribute to differences between closely related species that prevent gene exchange, particularly hybrid male sterility and female species preferences. we have examined the genetic basis of hybrid sterility and female species preferences in drosophila pseudoobscura and drosophila persimilis, two occasionally hybridizing north american species. contrary to findings in other species groups, very few regions of the genome were associated with t ... | 2001 | 11593019 |
| complex epistasis and the genetic basis of hybrid sterility in the drosophila pseudoobscura bogota-usa hybridization. | we analyzed the genetic basis of postzygotic isolation between the bogota and usa subspecies of drosophila pseudoobscura. these subspecies diverged very recently (perhaps as recently as 155,000 to 230,000 years ago) and are partially reproductively isolated: bogota and usa show very little prezygotic isolation but form sterile f1 males in one direction of the hybridization. we dissected the basis of this hybrid sterility and reached four main conclusions. first, postzygotic isolation appears to ... | 2001 | 11454758 |
| adult female drosophila pseudoobscura survive and carry fertile sperm through long periods in the cold: populations are unlikely to suffer substantial bottlenecks in overwintering. | to assess whether, while overwintering, natural populations of drosophila pseudoobscura are likely to experience substantial bottlenecks in their numbers and genotypes, laboratory tests of the cold sensitivities of each stage of the life history and reproduction were undertaken. three genetically distinctive lineages established from flies caught at high elevation were used for testing in temperatures likely to persist in protected pockets of fermenting deciduous leaf fall in overwintering sites ... | 2001 | 11392402 |
| molecular population genetics of sequence length diversity in the adh region of drosophila pseudoobscura. | positive and negative selection on indel variation may explain the correlation between intron length and recombination levels in natural populations of drosophila. a nucleotide sequence analysis of the 3.5 kilobase sequence of the alcohol dehydrogenase (adh) region from 139 drosophila pseudoobscura strains and one d. miranda strain was used to determine whether positive or negative selection acts on indel variation in a gene that experiences high levels of recombination. a total of 30 deletion a ... | 2002 | 12688655 |
| mutual interest between the sexes and reproductive success in drosophila pseudoobscura. | the pre-mating behavior of female drosophila pseudoobscura has been considered passive and "coy" relative to more active, "ardent," and indiscriminate male behavior. to test whether this long-held view-the "received wisdom" about mating behavior in drosophila-is really true we carried out observations on how often d. pseudoobscura females approached males prior to courtship and copulation. by including only virgin females and males in the experiments, we eliminated the possibility that males are ... | 2002 | 12583593 |