| estimating the parameters of selection on nonsynonymous mutations in drosophila pseudoobscura and d. miranda. | we present the results of surveys of diversity in sets of >40 x-linked and autosomal loci in samples from natural populations of drosophila miranda and d. pseudoobscura, together with their sequence divergence from d. affinis. mean silent site diversity in d. miranda is approximately one-quarter of that in d. pseudoobscura; mean x-linked silent diversity is about three-quarters of that for the autosomes in both species. estimates of the distribution of selection coefficients against heterozygous ... | 2010 | 20516497 |
| adaptive evolution of genes duplicated from the drosophila pseudoobscura neo-x chromosome. | drosophila x chromosomes are disproportionate sources of duplicated genes, and these duplications are usually the result of retrotransposition of x-linked genes to the autosomes. the excess duplication is thought to be driven by natural selection for two reasons: x chromosomes are inactivated during spermatogenesis, and the derived copies of retroposed duplications tend to be testis expressed. therefore, autosomal derived copies of retroposed genes provide a mechanism for their x-linked paralogs ... | 2010 | 20351054 |
| translocation of y-linked genes to the dot chromosome in drosophila pseudoobscura. | one of the most striking cases of sex chromosome reorganization in drosophila occurred in the lineage ancestral to drosophila pseudoobscura, where there was a translocation of y-linked genes to an autosome. these genes went from being present only in males, never recombining, and having an effective population size of 0.5n to a state of autosomal linkage, where they are passed through both sexes, may recombine, and their effective population size has quadrupled. these genes appear to be function ... | 2010 | 20147437 |
| the quantitative genetics and coevolution of male and female reproductive traits. | studies of experimental sexual selection have tested the effect of variation in the intensity of sexual selection on male investment in reproduction, particularly sperm. however, in several species, including drosophila pseudoobscura, no sperm response to experimental evolution has occurred. here, we take a quantitative genetics approach to examine whether genetic constraints explain the limited evolutionary response. we quantified direct and indirect genetic variation, and genetic correlations ... | 2010 | 20100215 |
| increased opportunity for sexual conflict promotes harmful males with elevated courtship frequencies. | mating systems have a profound influence on the probability of conflict occurring between the sexes. promiscuity is predicted to generate sexual conflict, thereby driving the evolution of male traits that harm females, whereas monogamy is expected to foster reproductive cooperation, thus rendering such traits redundant. we tested these predictions using experimentally evolved drosophila pseudoobscura subject to different mating systems. female survival was not influenced by the mating system tre ... | 2010 | 20039999 |
| evolution of sex-dependent gene expression in three recently diverged species of drosophila. | sexual dimorphism in morphological, physiological, and behavioral traits is pervasive in animals, as is the observation of strong sexual dimorphism in genomewide patterns of gene expression in the few species where this has been studied. studies of transcriptome divergence show that most interspecific transcriptional divergence is highly sex dependent, an observation consistent with the action of sex-dependent natural selection during species divergence. however, few transcriptome evolution stud ... | 2009 | 19720861 |
| evolutionary dynamics of recently duplicated genes: selective constraints on diverging paralogs in the drosophila pseudoobscura genome. | duplicated genes produce genetic variation that can influence the evolution of genomes and phenotypes. in most cases, for a duplicated gene to contribute to evolutionary novelty it must survive the early stages of divergence from its paralog without becoming a pseudogene. i examined the evolutionary dynamics of recently duplicated genes in the drosophila pseudoobscura genome to understand the factors affecting these early stages of evolution. paralogs located in closer proximity have higher sequ ... | 2009 | 19536449 |
| a test and review of the role of effective population size on experimental sexual selection patterns. | experimental evolution, particularly experimental sexual selection in which sexual selection strength is manipulated by altering the mating system, is an increasingly popular method for testing evolutionary theory. concerns have arisen regarding genetic diversity variation across experimental treatments: differences in the number and sex ratio of breeders (effective population size; n(e)) and the potential for genetic hitchhiking, both of which may cause different levels of genetic variation bet ... | 2009 | 19473403 |
| repeat mediated gene duplication in the drosophila pseudoobscura genome. | genetic mutations can occur on a wide variety of scales, including those that change single nucleotides, those that add or remove content to/from a genome, and those that change the organization of a genome. gene duplications are a specific class of mutations that add content to a genome, and they can arise via a wide variety of mechanisms. i examined the mechanisms responsible for recently duplicated genes in the d. pseudoobscura genome, and i observed both retroposed and dna duplications. many ... | 2009 | 19272434 |
| experimental manipulation of sexual selection promotes greater male mating capacity but does not alter sperm investment. | sexual selection theory makes clear predictions regarding male spermatogenic investment. to test these predictions we used experimental sexual selection in drosophila pseudoobscura, a sperm heteromorphic species in which males produce both fertile and sterile sperm, the latter of which may function in postmating competition. specifically, we determined whether the number and size of both sperm types, as well as relative testis mass and accessory gland size, increased with increased sperm competi ... | 2009 | 19236477 |
| a single gene causes both male sterility and segregation distortion in drosophila hybrids. | a central goal of evolutionary biology is to identify the genes and evolutionary forces that cause speciation, the emergence of reproductive isolation between populations. despite the identification of several genes that cause hybrid sterility or inviability-many of which have evolved rapidly under positive darwinian selection-little is known about the ecological or genomic forces that drive the evolution of postzygotic isolation. here, we show that the same gene, overdrive, causes both male ste ... | 2009 | 19074311 |
| selfish genetic elements promote polyandry in a fly. | it is unknown why females mate with multiple males when mating is frequently costly and a single copulation often provides enough sperm to fertilize all a female's eggs. one possibility is that remating increases the fitness of offspring, because fertilization success is biased toward the sperm of high-fitness males. we show that female drosophila pseudoobscura evolved increased remating rates when exposed to the risk of mating with males carrying a deleterious sex ratio-distorting gene that als ... | 2008 | 19023079 |
| selection in heterogeneous environments maintains the gene arrangement polymorphism of drosophila pseudoobscura. | chromosomal rearrangements may play an important role in how populations adapt to a local environment. the gene arrangement polymorphism on the third chromosome of drosophila pseudoobscura is a model system to help determine the role that inversions play in the evolution of this species. the gene arrangements are the likely target of strong selection because they form classical clines across diverse geographic habitats, they cycle in frequency over seasons, and they form stable equilibria in pop ... | 2008 | 18764919 |
| failure to replicate two mate preference qtls across multiple strains of drosophila pseudoobscura. | behavioral genetic mapping studies in model organisms predominantly use crosses originating from a single pair of inbred lines to determine the location of alleles that confer genetic variation in the trait of interest, and they often make sweeping generalizations about the genetic architecture of the trait based on these results. a previous study fine mapped mate preference variation between one pair of drosophila pseudoobscura lines and identified 2 strong-effect behavioral quantitative trait ... | 2017 | 18728083 |
| male-biased genes are overrepresented among novel drosophila pseudoobscura sex-biased genes. | the origin of functional innovation is among the key questions in biology. recently, it has been shown that new genes could arise from non-coding dna and that such novel genes are often involved in male reproduction. | 2008 | 18577217 |
| sexual selection and interacting phenotypes in experimental evolution: a study of drosophila pseudoobscura mating behavior. | sexual selection requires social interactions, particularly between the sexes. when trait expression is influenced by social interactions, such traits are called interacting phenotypes and only recently have the evolutionary consequences of interacting phenotypes been considered. here we investigated how variation in relative fitness, or the opportunity for sexual selection, affected the evolutionary trajectories of interacting phenotypes. we used experimentally evolved populations of the natura ... | 2008 | 18410532 |
| evolutionary biology: sterile saviours. | sterile sperm castes are widespread, but their significance remains enigmatic. new experiments on drosophila pseudoobscura reveal that sterile sperm may promote the survival of fertilising sperm inside the spermicidal female reproductive tract. | 2008 | 18364233 |
| a sterile sperm caste protects brother fertile sperm from female-mediated death in drosophila pseudoobscura. | spermicide (i.e., female-mediated sperm death) is an understudied but potentially widespread phenomenon that has important ramifications for the study of sexual conflict, postcopulatory sexual selection, and fertility [1, 2]. males are predicted to evolve adaptations against spermicide, but few antispermicidal mechanisms have been definitively identified. one such adaptation may be the enigmatic infertile sperm morphs or "parasperm" produced by many species, which have been hypothesized to prote ... | 2008 | 18291649 |
| divergence between the drosophila pseudoobscura and d. persimilis genome sequences in relation to chromosomal inversions. | as whole-genome sequence assemblies accumulate, a challenge is to determine how these can be used to address fundamental evolutionary questions, such as inferring the process of speciation. here, we use the sequence assemblies of drosophila pseudoobscura and d. persimilis to test hypotheses regarding divergence with gene flow. we observe low differentiation between the two genome sequences in pericentromeric and peritelomeric regions. we interpret this result as primarily a remnant of the correl ... | 2007 | 18039875 |
| global patterns of sequence evolution in drosophila. | sequencing of the genomes of several drosophila allows for the first precise analyses of how global sequence patterns change among multiple, closely related animal species. a basic question is whether there are characteristic features that differentiate chromosomes within a species or between different species. | 2007 | 17996078 |
| sexual conflict does not drive reproductive isolation in experimental populations of drosophila pseudoobscura. | sexual conflict has been predicted to drive reproductive isolation by generating arbitrary but rapid coevolutionary changes in reproductive traits among allopatric populations. a testable prediction of this proposal is that allopatric populations experiencing different levels of sexual conflict should exhibit different levels of reproductive isolation. we tested this prediction using experimentally evolved populations of the promiscuous drosophila pseudoobscura. we manipulated sexual conflict by ... | 2007 | 17714294 |
| meiotic transmission of drosophila pseudoobscura chromosomal arrangements. | drosophila pseudoobscura harbors a rich gene arrangement polymorphism on the third chromosome generated by a series of overlapping paracentric inversions. the arrangements suppress recombination in heterokaryotypic individuals, which allows for the selective maintenance of coadapted gene complexes. previous mapping experiments used to determine the degree to which recombination is suppressed in gene arrangement heterozygotes produced non-recombinant progeny in non-mendelian ratios. the deviation ... | 2007 | 17565383 |
| experimental constraints on mate preferences in drosophila pseudoobscura decrease offspring viability and fitness of mated pairs. | using drosophila pseudoobscura, we tested the hypothesis that social constraints on the free expression of mate preferences, by both females and males, decrease offspring viability and reproductive success of mating pairs. mate preference arenas eliminated intrasexual combat and intersexual coercion. the time female and male choosers spent in arena tests near either of two opposite-sex individuals measured the preferences of choosers. we placed choosers in breeding trials with their preferred or ... | 2007 | 17360550 |
| evolution of sex chromosomes: dosage compensation of the lcp1-4 gene cluster on the evolving neo-x chromosome in drosophila miranda. | in drosophila miranda the small multigene family of the larval cuticle protein (lcp1-4) genes resides on the evolving neo-x and neo-y sex chromosome pair while in the sibling species drosophila pseudoobscura and drosophila persimilis the gene cluster is inherited autosomally. the neo-y chromosomal lcp1, lcp2 and lcp4 genes are, as previously shown by us, not expressed and only lcp3 is expressed at a strongly reduced level. as a first step in understanding the evolutionary mechanism(s) transformi ... | 2007 | 17352708 |
| a short note on short dispersal events. | we study how the speed of spread for an integrodifference equation depends on the dispersal pattern of individuals. when the dispersal kernel has finite variance, the central limit theorem states that convolutions of the kernel with itself will approach a suitably chosen gaussian distribution. despite this fact, the speed of spread cannot be obtained from the gaussian approximation. we give several examples and explanations for this fact. we then use the kurtosis of the kernel to derive an impro ... | 2007 | 17318675 |
| evaluation of the genomic extent of effects of fixed inversion differences on intraspecific variation and interspecific gene flow in drosophila pseudoobscura and d. persimilis. | there is increasing evidence that chromosomal inversions may facilitate the formation or persistence of new species by allowing genetic factors conferring species-specific adaptations or reproductive isolation to be inherited together and by reducing or eliminating introgression. however, the genomic domain of influence of the inverted regions on introgression has not been carefully studied. here, we present a detailed study on the consequences that distance from inversion breakpoints has had on ... | 2007 | 17179068 |
| no accelerated rate of protein evolution in male-biased drosophila pseudoobscura genes. | sexually dimorphic traits are often subject to diversifying selection. genes with a male-biased gene expression also are probably affected by sexual selection and have a high rate of protein evolution. we used sage to measure sex-biased gene expression in drosophila pseudoobscura. consistent with previous results from d. melanogaster, a larger number of genes were male biased (402 genes) than female biased (138 genes). about 34% of the genes changed the sex-related expression pattern between d. ... | 2006 | 16816428 |
| rates and patterns of chromosomal evolution in drosophila pseudoobscura and d. miranda. | comparisons of gene orders between species permit estimation of the rate of chromosomal evolution since their divergence from a common ancestor. we have compared gene orders on three chromosomes of drosophila pseudoobscura with its close relative, d. miranda, and the distant outgroup species, d. melanogaster, by using the public genome sequences of d. pseudoobscura and d. melanogaster and approximately 50 in situ hybridizations of gene probes in d. miranda. we find no evidence for extensive tran ... | 2006 | 16547107 |
| a recombinational portrait of the drosophila pseudoobscura genome. | drosophila pseudoobscura has been intensively studied by evolutionary biologists for over 70 years. the recent publication of the genome sequence not only permits studies of comparative genomics with other dipterans but also opens the door to identifying genes associated with adaptive traits or speciation or testing for the signature of natural selection across the genome. information on regional rates of recombination, localization of inversion breakpoints distinguishing it from its sibling spe ... | 2006 | 16545148 |
| simulating natural conditions in the laboratory: a re-examination of sexual isolation between sympatric and allopatric populations of drosophila pseudoobscura and d. persimilis. | simulating natural conditions in the laboratory poses one of the most significant challenges to behavioral studies. some authors have argued that laboratory "choice" experiments reflect mate choice in nature more accurately than "no-choice" experiments. a recent choice experiment study questioned the conclusions of several earlier studies by failing to detect a published difference in sexual isolation between populations of drosophila pseudoobscura, and suggested their result was more robust bec ... | 2006 | 16502138 |
| a further analysis of sexual isolation between sympatric and allopatric populations of drosophila pseudoobscura and d. persimilis : rejoinder to noor and ortíz-barrientos. | | 2006 | 16477520 |
| evidence for a one-allele assortative mating locus. | theoretical models have shown that speciation with gene flow can occur readily via a "one-allele mechanism," where the spread of the same allele within both of two diverging species reduces their subsequent hybridization. here we present direct genetic evidence for such an allele in drosophila pseudoobscura. alleles conferring high or low assortative mating in d. pseudoobscura produce the same effects when inserted into d. persimilis. this observation suggests that the type of genetic variation ... | 2005 | 16322450 |
| the detection of shared and ancestral polymorphisms. | there is increasing evidence that closely related species contain many polymorphisms that were present in their common ancestral species. use of a more distant relative as an outgroup increases the ability to detect such ancestral polymorphisms. we describe a method for further improving estimates of the fraction of polymorphisms that are ancestral, and illustrate this with reference to data on drosophila pseudoobscura and d. miranda. we also derive formulae for the proportion of fixations arisi ... | 2005 | 16207392 |
| likelihoods from summary statistics: recent divergence between species. | we describe an importance-sampling method for approximating likelihoods of population parameters based on multiple summary statistics. in this first application, we address the demographic history of closely related members of the drosophila pseudoobscura group. we base the maximum-likelihood estimation of the time since speciation and the effective population sizes of the extant and ancestral populations on the pattern of nucleotide variation at dps2002, a noncoding region tightly linked to a p ... | 2005 | 16143628 |
| mechanisms of genetic exchange within the chromosomal inversions of drosophila pseudoobscura. | we have used the inversion system of drosophila pseudoobscura to investigate how genetic flux occurs among the gene arrangements. the patterns of nucleotide polymorphism at seven loci were used to infer gene conversion events between pairs of different gene arrangements. we estimate that the average gene conversion tract length is 205 bp and that the average conversion rate is 3.4 x 10(-6), which is 2 orders of magnitude greater than the mutation rate. we did not detect gene conversion events be ... | 2005 | 16143625 |
| postmating-prezygotic isolation is not an important source of selection for reinforcement within and between species in drosophila pseudoobscura and d. persimilis. | most work on adaptive speciation to date has focused on the role of low hybrid fitness as the force driving reinforcement (the evolution of premating isolation after secondary contact that reduces the likelihood of matings between populations). however, recent theoretical work has shown that postmating, prezygotic incompatibilities may also be important in driving premating isolation. we quantified premating, postmating-prezygotic, and early postzygotic fitness effects in crosses among three pop ... | 2005 | 16136803 |
| sexual isolation between sympatric and allopatric populations of drosophila pseudoobscura and d. persimilis. | according to reinforcement theory, sexual isolation between species in sympatry is strengthened by natural selection against maladaptive hybrids. drosophila pseudoobscura and d. persimilis from four locations where these species are sympatric, and from three locations where only d. pseudoobscura has been found, were utilized in studies of sexual isolation. multiple-choice observation chambers were used to record matings between sympatric and allopatric strains of the two species. there was a wid ... | 2005 | 15864445 |
| experimental manipulation of sexual selection and the evolution of courtship song in drosophila pseudoobscura. | courtship song serves as a sexual signal and may contribute to reproductive isolation between closely related species. using lines of drosophila pseudoobscura experimentally selected under different sexual selection regimes, we tested whether increased promiscuity and enforced monogamy led to evolutionary changes in courtship song elements. in d. pseudoobscura, males produce both a low and high rate repetition song. we found that both song types diverged after selection and that the direction of ... | 2005 | 15864440 |
| the genetic basis of reproductive isolation: insights from drosophila. | recent studies of the genetics of speciation in drosophila have focused on two problems: (i) identifying and characterizing the genes that cause reproductive isolation, and (ii) determining the evolutionary forces that drove the divergence of these "speciation genes." here, i review this work. i conclude that speciation genes correspond to ordinary loci having normal functions within species. these genes fall into several functional classes, although a role in transcriptional regulation could pr ... | 2005 | 15851676 |
| sex chromosomes: evolution of the weird and wonderful. | new findings in the platypus and drosophila pseudoobscura illustrate, yet again, that the sex chromosomes seem never to stop evolving. degeneration processes lead to a continual loss of genes and gene activity on the y chromosome, and complete loss of y-linked genes is possible if autosomal genes take over control of male fertility - though addition of new material to the sex chromosomes may start the process anew. | 2005 | 15723783 |
| segregation distortion in hybrids between the bogota and usa subspecies of drosophila pseudoobscura. | we show that, contrary to claims in the literature, "sterile" males resulting from the cross of the bogota and usa subspecies of drosophila pseudoobscura are weakly fertile. surprisingly, these hybrid males produce almost all daughters when crossed to females of any genotype (pure bogota, pure usa, hybrid f1). several lines of evidence suggest that this sex ratio distortion is caused by sex chromosome segregation distortion in hybrid males. we genetically analyze this normally cryptic segregatio ... | 2005 | 15654115 |
| y chromosome of d. pseudoobscura is not homologous to the ancestral drosophila y. | we report a genome-wide search of y-linked genes in drosophila pseudoobscura. all six identifiable orthologs of the d. melanogaster y-linked genes have autosomal inheritance in d. pseudoobscura. four orthologs were investigated in detail and proved to be y-linked in d. guanche and d. bifasciata, which shows that less than 18 million years ago the ancestral drosophila y chromosome was translocated to an autosome in the d. pseudoobscura lineage. we found 15 genes and pseudogenes in the current y o ... | 2005 | 15528405 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| sex chromosome loss induced by the "sex-ratio" trait in drosophila pseudoobscura males. | frequencies of sex chromosome aneuploid sperm were measured for standard and "sex-ratio" drosophila pseudoobscura males with identical genetic backgrounds. the "sex-ratio" males produced a 15.6-fold higher frequency of nullo-xy sperm than the standard males produced, but diplo-xy sperm were produced at the same rate in the two types of males. "sex-ratio" males with the same sr chromosome but with different chromosome backgrounds were found to produce different frequencies of sterile sons. these ... | 2003 | 1578108 |
| 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 |