Publications

a test of the chromosomal rearrangement model of speciation in drosophila pseudoobscura.	recent studies suggest that chromosomal rearrangements play a significant role in speciation by preventing recombination and maintaining species persistence despite interspecies gene flow. factors conferring adaptation or reproductive isolation are maintained in rearranged regions in the face of hybridization, while such factors are eliminated from collinear regions. as a direct test of this rearrangement model, we evaluated the genetic basis of hybrid male sterility in a sympatric species pair, ...	2004	15446438
genetics of natural populations. xix. origin of heterosis through natural selection in populations of drosophila pseudoobscura.		1950	15414931
computational identification of developmental enhancers: conservation and function of transcription factor binding-site clusters in drosophila melanogaster and drosophila pseudoobscura.	the identification of sequences that control transcription in metazoans is a major goal of genome analysis. in a previous study, we demonstrated that searching for clusters of predicted transcription factor binding sites could discover active regulatory sequences, and identified 37 regions of the drosophila melanogaster genome with high densities of predicted binding sites for five transcription factors involved in anterior-posterior embryonic patterning. nine of these clusters overlapped known ...	2004	15345045
analysis of the insect os-d-like gene family.	insect os-d-like proteins, also known as chemosensory (csp) or sensory appendage proteins (sap), are broadly expressed in various insect tissues, where they are thought to bind short to medium chain length fatty acids and their derivatives. although their specific function remains uncertain, os-d-like members have been isolated from sensory organs (including the sensillum lymph in some cases), and a role in olfaction similar to that of the insect odorant binding proteins (obp) has been suggested ...	2004	15274438
multilocus methods for estimating population sizes, migration rates and divergence time, with applications to the divergence of drosophila pseudoobscura and d. persimilis.	the genetic study of diverging, closely related populations is required for basic questions on demography and speciation, as well as for biodiversity and conservation research. however, it is often unclear whether divergence is due simply to separation or whether populations have also experienced gene flow. these questions can be addressed with a full model of population separation with gene flow, by applying a markov chain monte carlo method for estimating the posterior probability distribution ...	2004	15238526
evolution of the trans-splicing drosophila locus mod(mdg4) in several species of diptera and lepidoptera.	the modifier of mdg4 (mod[mdg4]) locus of drosophila melanogaster (dme) encodes chromatin proteins which are involved in position effect variegation, establishment of chromatin boundaries, nerve pathfinding, meiotic chromosome pairing and apoptosis. it was recently shown that mrna trans-splicing is involved in the generation of at least 26 different mod(mdg4) transcripts. here, we show that a similar complex mod(mdg4) locus exists in drosophila pseudoobscura (dps), drosophila virilis (dvi), anop ...	2004	15094203
molecular evolution of x-linked accessory gland proteins in drosophila pseudoobscura.	in drosophila melanogaster and drosophila simulans, positive darwinian selection drives high rates of evolution of male reproductive genes, and accessory gland proteins (acps) in particular. here, we tested whether 13 x-linked male-specific genes, 4 acps and 9 non-acps, are under selective forces in the drosophila pseudoobscura species group, much as those in the d. melanogaster group. we observed a statistically significant correlation in relative rates of nonsynonymous evolution between the tw ...	2004	15073226
conservation of dna methylation in dipteran insects.	dna methylation is a central mechanism of epigenetic regulation. whereas vertebrate dna methylation requires at least four different dna methyltransferases, drosophila melanogaster only utilizes a single, dnmt2-like enzyme. this profound difference has raised the question of the evolutionary significance of the drosophila methylation system. we have now identified dnmt2-like open reading frames in the genome sequences of drosophila pseudoobscura and anopheles gambiae. these genes represent the o ...	2004	15056358
computational identification of microrna targets.	recent experiments have shown that the genomes of organisms such as worm, fly, human, and mouse encode hundreds of microrna genes. many of these micrornas are thought to regulate the translational expression of other genes by binding to partially complementary sites in messenger rnas. phenotypic and expression analysis suggests an important role of micrornas during development. therefore, it is of fundamental importance to identify microrna targets. however, no experimental or computational high ...	2004	15013811
detection of stabilizing selection in favor of the santa cruz homokaryotype in drosophila pseudoobscura populations from the high plateau of the colombian andes.	chromosome 3 rearrangements were studied in five drosophila pseudoobscura populations from the high plateau of the colombian andes. as in previous studies, the santa cruz and tree line rearrangements were predominant in these populations, but for the first time other rearrangements such as the olympic, cuernavaca and a rearrangement similar to the endemic mexican amecameca rearrangement were also discovered. researchers in the early 1960's showed that colombian d. pseudoobscura populations were ...	2002	14963809
"plus-c" odorant-binding protein genes in two drosophila species and the malaria mosquito anopheles gambiae.	olfaction plays a crucial role in many aspects of insect behaviour, including host selection by agricultural pests and vectors of human disease. insect odorant-binding proteins (obps) are thought to function as the first step in molecular recognition and the transport of semiochemicals. the whole genome sequence of the fruit fly drosophila melanogaster has been completed and a large number of genes have been annotated as obps, based on the presence of six conserved cysteine residues and a conser ...	2004	14960367
morphological differences between two sibling species; drosophila pseudoobscura and drosophila persimilis.		1951	14808171
unusual pattern of single nucleotide polymorphism at the exuperantia2 locus of drosophila pseudoobscura.	we have investigated the pattern of dna sequence variation at the exuperantia2 locus in drosophila pseudoobscura. this adds to the increasing dataset of genetic variation in d. pseudoobscura, a useful model species for evolutionary genetic studies. the level of silent site nucleotide diversity and the divergence from an outgroup drosophila miranda are comparable with those for other x-linked loci. one peculiar pattern at the exu2 locus of d. pseudoobscura is a complete linkage disequilibrium bet ...	2003	14768894
the drosophila gene start1: a putative cholesterol transporter and key regulator of ecdysteroid synthesis.	human metastatic lymph node 64 (mln64) is a transmembrane protein that shares homology with the cholesterol-binding vertebrate steroid acute regulatory protein (star)-related lipid transfer domain (start) and is involved in cholesterol traffic and steroid synthesis. we identified a drosophila melanogaster gene whose putative protein product shows extensive homology with mln64 and that we name start1 (flybase cg3522). the putative start1 protein, derived from start1 cdna sequences, contains an ad ...	2004	14745013
transcription of drosophila troponin i gene is regulated by two conserved, functionally identical, synergistic elements.	the drosophila wings-up a gene encodes troponin i. two regions, located upstream of the transcription initiation site (upstream regulatory element) and in the first intron (intron regulatory element), regulate gene expression in specific developmental and muscle type domains. based on lacz reporter expression in transgenic lines, upstream regulatory element and intron regulatory element yield identical expression patterns. both elements are required for full expression levels in vivo as indicate ...	2004	14718563
phylogenetic relationships of drosophila melanogaster species group deduced from spacer regions of histone gene h2a-h2b.	nucleotide sequences of the spacer region of the histone gene h2a-h2b from 36 species of drosophila melanogaster species group were determined. the phylogenetic trees were reconstructed with maximum parsimony, maximum likelihood, and bayesian methods by using drosophila pseudoobscura as the out group. our results show that the melanogaster species group clustered in three main lineages: (1). montium subgroup; (2). ananassae subgroup; and (3). the seven oriental subgroups, among which the montium ...	2004	14715225
microrna targets in drosophila.	the recent discoveries of microrna (mirna) genes and characterization of the first few target genes regulated by mirnas in caenorhabditis elegans and drosophila melanogaster have set the stage for elucidation of a novel network of regulatory control. we present a computational method for whole-genome prediction of mirna target genes. the method is validated using known examples. for each mirna, target genes are selected on the basis of three properties: sequence complementarity using a position- ...	2003	14709173
characterization of a male-predominant antisense transcript underexpressed in hybrids of drosophila pseudoobscura and d. persimilis.	characterizing genes that are misregulated in hybrids may elucidate the genetic basis of hybrid sterility or other hybrid dysfunctions that contribute to speciation. previously, a small segment of a male-predominant transcript that is underexpressed in adult male hybrids of drosophila pseudoobscura and d. persimilis relative to pure species was identified in a differential display screen. here, we obtained the full sequence of this 1330-bp transcript and determined that it is an antisense messag ...	2003	14704168
evolutionary rearrangement of the amylase genomic regions between drosophila melanogaster and drosophila pseudoobscura.	two drosophila pseudoobscura genomic clones have sequence similarity to the drosophila melanogaster amylase region that maps to the 53cd region on the d. melanogaster cytogenetic map. the two clones with similarity to amylase map to sections 73a and 78c of the d. pseudoobscura third chromosome cytogenetic map. the complete sequences of both the 73a and 78c regions were compared to the d. melanogaster genome to determine if the coding region for amylase is present in both regions and to determine ...	2006	14691313
divergent environments and population bottlenecks fail to generate premating isolation in drosophila pseudoobscura.	while the feasibility of bottleneck-induced speciation is in doubt, population bottlenecks may still affect the speciation process by interacting with divergent selection. to explore this possibility, i conducted a laboratory speciation experiment using drosophila pseudoobscura involving 78 replicate populations assigned in a two-way factorial design to both bottleneck (present vs. absent) and environment (ancestral vs. novel) treatments. populations independently evolved under these treatments ...	2003	14686531
indiscriminate females and choosy males: within- and between-species variation in drosophila.	the classic view of choosy, passive females and indiscriminate, competitive males gained theoretical foundations with parental investment theory. when females invest more in offspring than males, parental investment theory says that selection operates so that females discriminate among males for mates (i.e., females are choosy and passive) and males are indiscriminate (i.e., males are profligate and competitive). here we report tests of predictions using drosophila pseudoobscura and d. melanogas ...	2003	14575325
bichromosomal synthetic semilethals in drosophila pseudoobscura.		1965	14338225
experimental control over the evolution of fitness in laboratory populations of drosophila pseudoobscura.		1965	14326055
genetic divergence in m. vetukhiv's experimental populations of drosophila pseudoobscura. 2. longevity.		1965	14297592
cytological basis of "sex ratio" in drosophila pseudoobscura.	cytological investigations of both laboratory and wild "sex ratio" lines of drosophila pseudoobscura reveal that, contrary to earlier reports, no extra replication of the x chromosome occurs in primary spermatocytes. normal disjunction of the sex chromosomes at anaphase i leads to equal numbers of x-bearing and y-bearing secondary spermatocytes. in the latter, the y chromosome regularly shows a "degeneration" at second anaphase. the "sex ratio" effect can be explained in terms of regularly nonfu ...	1965	14263775
genetic loads in irradiated experimental populations of drosophila pseudoobscura.		1964	14239789
lethal and semilethal chromosomes in irradiated experimental populations of drosophila pseudoobscura.		1964	14239788
inbreeding and viability in experimental populations of drosophila pseudoobscura.		1964	14231442
the capacity for increase in chromosomally polymorphic and monomorphic populations of drosophila pseudoobscura.		1964	14221018
mating speed control by gene arrangements in drosophila pseudoobscura homokaryotypes.		1964	14215621
genetics of natural populations. xxxiv. adaptive norm, genetic load and genetic elite in drosophila pseudoobscura.		1963	14083044
comparative fitness of experimental populations of drosophila pseudoobscura.		1963	14080688
effects of temperature and x-ray irradiation on intrinsic growth rate in populations of drosophila pseudoobscura.		1963	14058260
genetics of natural populations. 32. inbreeding and the mutational and balanced genetic loads in natural populations of drosophila pseudoobscura.		1963	14028273
genetics of natural populations. xxxi. genetics of an isolated marginal population of drosophila pseudoobscura.		1963	14028271
temperature sensitivity of chromosomal polymorphism in drosophila pseudoobscura.		1962	13996135
genetic studies of natural populations of drosophila: drosophila pseudoobscura, a large dominant population.		1963	13984396
selection and body size in drosophila pseudoobscura at different temperatures.		1962	13887953
genetic drift and natural selection in experimental populations of drosophila pseudoobscura.		1962	13886810
effects of temperature on productivity and genetic variance of body size in populations of drosophila pseudoobscura.		1961	13775221
the longevity of hybrids between local populations of drosophila pseudoobscura.		1957	13410487
drosophila lola encodes a family of btb-transcription regulators with highly variable c-terminal domains containing zinc finger motifs.	alternative splicing is an important mechanism contributing to the increased proteome diversity in higher eukaryotes. we have explored the alternative splicing events in the drosophila longitudinals lacking (lola) gene by means of 5' race, 3' race, genome sequence searches, and est sequencing. we demonstrated that the lola locus is comprised of 32 exons spanning over 60 kb, and encodes a total of 80 alternatively spliced variants consisting of 5' and 3' variable sequences and constitutive common ...	2003	12853139
evolution of gab family adaptor proteins.	the gab/dos/soc-1 proteins form a family of multi-adaptor/scaffolding proteins involved in receptor tyrosine kinase signaling. to further understanding of the gab family and the drosophila dos protein in particular, we isolated a dos homolog from both drosophila pseudoobscura and drosophila virilis and compared their gene structures and protein sequences with the rest of the gab family. the presence of two conserved introns confirmed that the dos and gab genes are orthologous, but the caenorhabd ...	2003	12853137
evolutionary genomics of inversions in drosophila pseudoobscura: evidence for epistasis.	drosophila pseudoobscura harbors a rich polymorphism for paracentric inversions on the third chromosome, and the clines in the inversion frequencies across the southwestern united states indicate that strong natural selection operates on them. isogenic inversion strains were made from isofemale lines collected from four localities, and eight molecular markers were mapped on the third chromosome. nucleotide diversity was measured for these loci and formed the basis of an evolutionary genomic anal ...	2003	12824467
the causes of phylogenetic conflict in a classic drosophila species group.	bifurcating phylogenies are frequently used to describe the evolutionary history of groups of related species. however, simple bifurcating models may poorly represent the evolutionary history of species that have been exchanging genes. here, we show that the history of three well-known closely related species, drosophila pseudoobscura, d. persimilis and d. p. bogotana, is not well represented by a bifurcating phylogenetic tree. the phylogenetic relationships among these species vary widely betwe ...	2003	12816659
phospholipase c-gamma contains introns shared by src homology 2 domains in many unrelated proteins.	many proteins with novel functions were created by exon shuffling around the time of the metazoan radiation. phospholipase c-gamma (plc-gamma) is typical of proteins that appeared at this time, containing several different modules that probably originated elsewhere. to gain insight into both plc-gamma evolution and structure-function relationships within the drosophila plc-gamma encoded by small wing (sl), we cloned and sequenced the plc-gamma homologs from drosophila pseudoobscura and d. virili ...	2003	12807765
turnover of binding sites for transcription factors involved in early drosophila development.	despite the importance of cis-regulatory regions in evolution, little is know about their evolutionary dynamics. in this report, we analyze the process of evolution of binding sites for transcription factors using as a model a well characterized system, the drosophila early developmental enhancers. we compare the sequences of eight enhancer regions for early developmental genes between drosophila melanogaster and other two species, drosophila virilis and drosophila pseudoobscura, searching for t ...	2003	12801649
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
the evolution of conspecific sperm precedence in drosophila.	conspecific sperm precedence takes place when females inseminated by both conspecific and heterospecific sperm preferentially produce conspecific rather than hybrid offspring. although many studies have documented conspecific sperm precedence, most have only identified it between taxa that are already considered to be good species. here, we test for sperm precedence between two drosophila pseudoobscura subspecies and between two drosophila melanogaster races to evaluate how early in evolutionary ...	2003	12694281
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
strong founder effect in drosophila pseudoobscura colonizing new zealand from north america.	the north american native species drosophila pseudoobscura was first identified in new zealand in the last few decades. here, we have studied the genetic consequences of its spread across the pacific ocean. using 10 microsatellites that are highly variable in north american populations, we found that the new zealand population has substantially fewer alleles, a much lower average heterozygosity, and significantly different allele frequencies at these loci. we have discussed the relative sensitiv ...	2002	12642641
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
little qualitative rna misexpression in sterile male f1 hybrids of drosophila pseudoobscura and d. persimilis.	although the genetics of hybrid sterility has been the subject of evolutionary studies for over sixty years, no one has shown the reason(s) why alleles that operate normally within species fail to function in another genetic background. several lines of evidence suggest that failures in normal gene transcription contribute to hybrid dysfunctions, but genome-wide studies of gene expression in pure-species and hybrids have not been undertaken. here, we study genome-wide patterns of expression in d ...	2002	12223116
inferring the history of speciation from multilocus dna sequence data: the case of drosophila pseudoobscura and close relatives.	the divergence of drosophila pseudoobscura from its close relatives, d. persimilis and d. pseudoobscura bogotana, was examined using the pattern of dna sequence variation in a common set of 50 inbred lines at 11 loci from diverse locations in the genome. drosophila pseudoobscura and d. persimilis show a marked excess of low-frequency variation across loci, consistent with a model of recent population expansion in both species. the different loci vary considerably, both in polymorphism levels and ...	2002	11919289
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
age-specific fitness components in hybrid females of drosophila pseudoobscura and d. persimilis.	most models of hybridization assume that hybrids are less fit than their parental taxa. in contrast, some researchers have explored the possibility that hybrid individuals may actually have higher fitness and so play an important role in the generation of new species or adaptations. by estimating age-specific fitness components, we can determine not only how hybrid fitness differs from parental taxa, but also whether the fitness of hybrids relative to parental taxa changes with age. here we desc ...	2009	11336226
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
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
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
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
recombination, statistical power, and genetic studies of sexual isolation in drosophila.	genetic studies of sexual isolation in drosophila have generally failed to fully evaluate the effects of their sample size and recombination between markers on their conclusions. in this study we evaluate recombinational distances between markers in drosophila pseudoobscura and d. persimilis, a species pair in which numerous genetic mapping studies have been performed. we conclude that, contrary to assertions, the inversions that distinguish these two species still allow for much recombination w ...	2007	10768121
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
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
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
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
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
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
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
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
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
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
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
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
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
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 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
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
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
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
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
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
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
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
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
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
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