| perturbation-reperturbation test of selection vs. hitchhiking of the two major alleles of esterase-5 in drosophila pseudoobscura. | a perturbation-reperturbation tests selective neutrality of 100/100/100/100/100 and 106/100/100/100/100, the two most common alleles at the highly polymorphic x-linked locus esterase-5 in drosophila pseudoobscura. a total of 22 replicate populations are set up in cages, 11 start at a high frequency of 76% (u) and 11 at a low frequency of 21% (n) of the 106 allele. allele frequencies change directionally and decrease in both u and n populations as groups and reach equilibria of 60 and 14%, respec ... | 1991 | 1936955 |
| coadaptation revisited. | during the four decades or more since dobzhansky introduced the term "coadaptation" to refer to the commonly observed selective superiority of inversion heterozygotes in populations of drosophila pseudoobscura, the definition of the term has evolved, as have views concerning the rapidity with which coadaptation might occur. indeed, the paucity of demonstrated instances of linkage disequilibrium in natural populations has led many to dismiss coadaptation as a factor in evolutionary change. the pr ... | 2010 | 1901579 |
| male-sex-ratio trait in drosophila pseudoobscura: frequency of autosomal aneuploid sperm. | males with the sr x chromosome show the "sex-ratio" (sr) phenotype in which they produce almost entirely daughters. the few sons (about 1%) are invariably sterile x/o males and result entirely from nullo-xy sperm. the "male-sex-ratio" (msr) phenotype is a modified form of sr in which sr/y males produce a higher frequency of sterile x/o sons. the msr trait is due to the presence of the sr x-chromosome in males which are also homozygous for one or more autosomes from the l116 strain. here the freq ... | 1991 | 2004709 |
| molecular evolution of inversions in drosophila pseudoobscura: the amylase gene region. | the amylase region of the third chromosome of drosophila pseudoobscura has been cloned and localized to cytological band 73a. it is contained within a series of highly polymorphic inversions and serves as a convenient tool for a molecular evolutionary analysis of the inverted gene arrangements. amylase in d. pseudoobscura is a family of three genes, and some chromosomes have deletions for one or two of them. two overlapping clones covering 26 kilobases were isolated and used as probes to survey ... | 1991 | 1702542 |
| cloning of the esterase-5 locus from drosophila pseudoobscura and comparison with its homologue in d. melanogaster. | a clone of the esterase-5 (est-5) gene from drosophila pseudoobscura has been isolated by hybridization to the cloned est-6 gene of d. melanogaster. southern analysis and sequencing of the cloned dna revealed three regions of similarity to est-6 that have been tentatively identified as genes, est-5a, est-5b, and est-5c. introduction of each of the three genes separately into d. melanogaster by p-element transformation has demonstrated that est-5b encodes an enzyme with the same physical properti ... | 1990 | 2178209 |
| developmental isolation and subsequent adult behavior of drosophila pseudoobscura. | when isolated from all contact with other flies until the opportunity to exercise mating choices, drosophila pseudoobscura displays genetically-mediated compensatory behavior: heterokaryotypic females are more vulnerable than homokaryotes to wholly restricted contact with conspecifics. they are less able to demonstrate normal frequency-dependent sexual selection after isolation than their own homokaryotypes. however, the later the isolation in this holometabolous insect--eggs, first instars, sec ... | 1990 | 2288548 |
| molecular analysis of the bicoid gene from drosophila pseudoobscura: identification of conserved domains within coding and noncoding regions of the bicoid mrna. | the specification of anterior positional information during drosophila embryogenesis is largely dependent upon the function of the maternal-effect gene bicoid (bcd). two aspects of bcd function are particularly striking. first, the bcd protein product forms a gradient during early embryogenesis, which regulates the transcription of at least one zygotic segmentation gene, hunchback, in a concentration dependent manner. secondly, formation of the bcd protein gradient is dependent upon the specific ... | 1990 | 1975239 |
| localization of genes causing postzygotic isolation in two hybridizations involving drosophila pseudoobscura. | the genes causing postzygotic isolation in two drosophila hybridizations were localized to regions of the x chromosome. the x has a large effect on d. pseudoobscura pseudoobscura ("u.s.a.")-d. pseudoobscura bogotana ("bogota") hybrid male sterility. recombination analysis shows that this effect is due entirely to a small chromosome region representing less than 20 per cent of the x. this result suggests that a single x-linked gene may be involved. a maximum likelihood mapping procedure places th ... | 1989 | 2807977 |
| selection in natural and experimental populations of drosophila pseudoobscura. | the inverted gene arrangements of drosophila pseudoobscura were used by th. dobzhansky in pioneering analyses of natural selection. recent experiments have shed light on the mechanisms of selection contributing to the balanced polymorphism for the gene arrangements. in experimental populations, both major components of fitness, viability and fertility, are frequency dependent, and rare genotypes often have a selective advantage. viabilities are also density dependent. the frequency dependence an ... | 1989 | 2687095 |
| nucleotide sequence of the xdh region in drosophila pseudoobscura and an analysis of the evolution of synonymous codons. | the nucleotide sequence of the xdh region of drosophila pseudoobscura is presented. the xdh gene structure and organization are compared with the homologous region in d. melanogaster. this locus is shown to have similar organization in the two species, although an additional intron and three insertion/deletion events are described for the d. pseudoobscura coding region. the encoded proteins are predicted to have very similar charges and hydrophobic/hydrophilic domains even though 11% of the amin ... | 1989 | 2493563 |
| interspecific comparison of the period gene of drosophila reveals large blocks of non-conserved coding dna. | we have cloned and sequenced the coding region of the period (per) gene from drosophila pseudoobscura and d. virilis. a comparison with that of d. melanogaster reveals that the conceptual translation products consist of interspersed blocks of conserved and non-conserved amino acid sequence. the non-conserved portion, comprising approximately 33% of the protein sequence, includes the perfect thr-gly repeat of d. melanogaster, which is absent from the d. pseudoobscura and d. virilis proteins. base ... | 1988 | 3208754 |
| rare male mating advantage in a natural population of drosophila pseudoobscura. | the natural selection acting on chromosomal inversions was studied in a natural population of drosophila pseudoobscura. females from this population were allowed to produce offspring from their matings in nature. they were then remated to males from a laboratory strain and again allowed to produce offspring. offspring were also produced from matings of males from nature to laboratory females. diagnosis of salivary chromosomes in these several sets of larval offspring allowed us to deduce the kar ... | 1988 | 3200863 |
| evidence for non-neutrality of mitochondrial dna haplotypes in drosophila pseudoobscura. | mitochondrial dna (mtdna) haplotypes usually are assumed to be neutral, unselected markers of evolving female lineages. this assumption was tested by monitoring haplotype frequencies in 12 experimental populations of drosophila pseudoobscura which were polymorphic for mtdna haplotypes. populations were maintained for at least 10 generations, and in one case for 32 generations, while tests of mtdna selective neutrality were conducted. in an initial population, formed from a mixture of two strains ... | 1988 | 3197957 |
| the effects of inbreeding and ventilation on mating behavior in drosophila pseudoobscura. | two outbred and two inbred lines of drosophila pseudoobscura were used in mating behavior studies. for each line, mating rates were compared under both ventilated and nonventilated conditions. under nonventilated conditions courtship and mating were earlier, not following a random rate of occurence, and females mated after fewer courtships. flies from inbred lines tended to court and mate earlier. under all conditions a high proportion of matings occured on the first courtship attempt. | 1987 | 24925652 |
| modifier genes of the sex ratio trait in drosophila pseudoobscura. | the msr trait of drosophila pseudoobscura occurs when "sex-ratio" males produce a very high frequency of null-x sperm which give rise to sterile male (x/o) progeny. the trait involves dramatically lowered fecundity due to spermiogenic failure. the msr trait is multigenic and the genes are located on autosomes ii, iii and iv of the l116 laboratory stock. this stock also carries genes on the y chromosome that lower the level of msr. when the genes on the l116 autosomes are present together or with ... | 1987 | 17246384 |
| genetic divergence under uniform selection. iii. selection for knockdown resistance to ethanol in drosophila pseudoobscura populations and their replicate lines. | replicate d. pseudoobscura lines from populations collected at different geographic locations were selected for increased knockdown resistance to ethanol. population background affected the initial rate of response but not the extent that lines responded. lines were tested for physiological traits contributing to increased knockdown resistance. populations showed different correlated responses for two traits (tolerance of ethanol, and of acetone), suggesting that they had responded to selection ... | 1987 | 3597126 |
| restriction-map variation in the alcohol dehydrogenase region of drosophila pseudoobscura. | a 32-kb region including the adh structural gene was analyzed with six restriction endonucleases in 20 lines of drosophila pseudoobscura, one line of d. persimilis, and one line of d. miranda. nineteen lines of d. pseudoobscura from a single population were estimated to be polymorphic at one in every 15 nucleotides (p = 0.066). any two homologous chromosomes chosen at random were heterozygous at one in 48 (h = 0.021) nucleotides. two small insertions of 50 and 200 bp were found approximately 7 k ... | 1987 | 2833670 |
| desiccation resistance in two species of drosophila. | three populations of drosophila pseudoobscura, each one represented by 12 isofemale lines, and one laboratory strain of d. melanogaster were tested for desiccation resistance at two time periods. except in the case of one population of d. pseudoobscura, the ability to withstand drying was significantly greater in females than in the corresponding males. the males of the three populations of d. pseudoobscura differed significantly among themselves in their resistance to desiccation, as did the fe ... | 2007 | 3772067 |
| an investigation of the genetics of "male sex-ratio" phenotype in drosophila pseudoobscura. | a laboratory strain of drosophila pseudoobscura (l116) is studied that, when crossed to sex-ratio homozygous females, produces sons that exhibit varying levels of the male sex-ratio (msr) phenotype. the msr phenotype occurs only in sex-ratio males and is due to the production of a high frequency of nullo-xy sperm. the level of the msr phenotype is variable, and new variability is generated in one father-son transmission. pedigree studies indicate the genes for msr reside on the y chromosome or t ... | 1986 | 17246330 |
| laboratory-induced changes in the mate recognition system of drosophila pseudoobscura. | | 1986 | 3718418 |
| habitat choice by drosophila pseudoobscura: the roles of genotype and of experience. | | 1986 | 3718416 |
| natural selection vs. random drift: evidence from temporal variation in allele frequencies in nature. | we have obtained monthly samples of two species, drosophila pseudoobscura and drosophila persimilis, in a natural population from napa county, california. in each species, about 300 genes have been assayed by electrophoresis for each of seven enzyme loci in each monthly sample from march 1972 to june 1975. using statistical methods developed for the purpose, we have examined whether the allele frequencies at different loci vary in a correlated fashion. the methods used do not detect natural sele ... | 1985 | 4054608 |
| mitochondrial dna variation in drosophila pseudoobscura and related species in pacific northwest populations. | we have analysed mitochondrial dna (mtdna) from pacific northwest populations of drosophila pseudoobscura, d. persimilis, and d. miranda using six restriction enzymes. we find that hpaii restriction sites are hypervariable compared to the other enzymes used. this hypervariability allows construction of a maximum parsimony map linking each mtdna genotype. small insertions, possibly tandem duplications, appear to have arisen concomitantly with, or subsequent to, speciation events, perhaps within t ... | 1985 | 3880378 |
| nearly identical allelic distributions of xanthine dehydrogenase in two populations of drosophila pseudoobscura. | in a previous study, keith (1983) showed by sequential gel electrophoresis of the esterase-5 protein in drosophila pseudoobscura that a highly polymorphic locus with many alleles can have very similar frequency distributions in populations separated by 500 km. the present work studies another highly polymorphic locus, xanthine dehydrogenase, in the same california population samples, using the same technique to distinguish allelic classes. twelve electromorphs were found in one population and 15 ... | 1985 | 3871004 |
| a test for rare male mating advantage with drosophila pseudoobscura karyotypes. | recent work has called into question the reality of the rare male mating advantage, pointing out that it could be a statistical artifact of marking flies for behavioral observation or of experimental bias in collecting males. we designed an experiment to test for rare male mating advantage that avoids these sources of bias. large numbers of males of three drosophila pseudoobscura karyotypes were allowed to mate with females of one karyotype in population cages. the females were then isolated bef ... | 1984 | 17246224 |
| a note on barometric pressure and behavior in drosophila pseudoobscura. | | 1984 | 6487232 |
| population genetics of drosophila amylase. v. genetic background and selection on different carbohydrates. | frequency changes in amylase allozymes and patterns of tissue-specific expression of amylase have been monitored in laboratory populations of drosophila pseudoobscura maintained on media in which the only carbohydrate source was maltose or starch. nonrandom changes occurred in patterns of expression, whereas no patterns in allozyme frequency changes were discernible. the nature of the pattern changes was similar to an identical study done on populations derived from a natural population several ... | 1984 | 17246202 |
| mitochondrial gene flow. | to account for the transmission of mitochondrial dna between conspecific species drosophila pseudoobscura and d. persimilis in sympatry reported by j.r. powell [powell, j.r. (1983) proc. natl. acad. sci. usa 80, 492-495], a simple model of gene flow and selection in infinite populations is analyzed. the model assumes two alleles at each of two loci, one of which is coded by an autosome and the other by mitochondrial dna. viability selection is presumed to be underdominant--i.e., heterozygous inf ... | 1984 | 6584909 |
| chromatin structure and transcriptional activity of an x-linked heat shock gene in drosophila pseudoobscura. | nuclease digestion of isolated nuclei was used to test whether differential chromatin structure exists for a dosage-compensated heat shock gene in drosophila pseudoobscura. no differences were observed in nuclease sensitivity at this locus in males and females, either under heat shock or non-heat shock conditions, using micrococcal nuclease or dnase i. although the higher level of nuclease sensitivity characterized by the induced state was removed when nuclei were prepared in high salt (0.45 m s ... | 1983 | 6315715 |
| virility deficiency and the sex-ratio trait in drosophila pseudoobscura. ii. multiple mating and overall virility selection. | previous studies on fitness components of drosophila have shown the over-whelming importance of virility selection. in this study, virility selection is further partitioned into two components-one with respect to virgin females and the other with respect to nonvirgin females. the relative importance of the two components to the overall virility selection depends on the remating tendency of females which is investigated here. a theoretical model is then proposed to estimate virility selection und ... | 1983 | 17246171 |
| virility deficiency and the sex-ratio trait in drosophila pseudoobscura. i. sperm displacement and sexual selection. | the sex-ratio (sr) phenomenon is associated with the x chromosome of many species of drosophila. males carrying sr transmit predominantly sperm bearing the x chromosome. sr, therefore, has a very significant advantage in segregation. this paper provides an experimental analysis of the role of virility selection in preventing the fixation of sr. sr males are found to suffer substantial virility reduction when mated with nonvirgin females but not with virgin females. the reduced virility arises be ... | 1983 | 17246170 |
| selection for light preference during ovipositing in drosophila pseudoobscura. | selection was carried out on a population of drosophila pseudoobscura to obtain lines preferring high-light intensity or low-light intensity during oviposition. this species is generally characterized as preferring low-light intensities. it was possible to select for increased preference for high-light intensity, but not for low-light intensity during oviposition. however, additive genetic variability exists in preferences for both high- and low-light intensities. the original population was pro ... | 1983 | 6652564 |
| evidence for extensive genetic differentiation between the sex-ratio and the standard arrangement of drosophila pseudoobscura and d. persimilis and identification of hybrid sterility factors. | this study deals with sex-ratio genes tightly linked within the sex-ratio inversion. by taking advantage of the fact that the sex-ratio chromosome of drosophila persimilis [sr(b)] is homosequential to the standard chromosome of d. pseudoobscura [st(a)], we carried out two reciprocal introgression experiments. individual segments of sr(b) or st(a) were introgressed into the genome of d. pseudoobscura or d. persimilis, respectively. males possessing a hybrid sr(b)-st(a) x chromosome and a genetic ... | 1983 | 17246158 |
| frequency distribution of esterase-5 alleles in two populations of drosophila pseudoobscura. | statistical tests comparing allele frequencies in natural populations with those predicted by various theories of genic variation depend critically on the accurate enumeration of alleles. this study used a series of five sequential electrophoretic conditions to characterize the allele frequency distributions of esterase-5 in two large population samples of drosophila pseudoobscura from california. in standard chromosome lines 12 electromorphs were discriminated using a single electrophoretic con ... | 1983 | 17246152 |
| population genetics in the american tropics : 18. the genetic structure of peripheral drosophila pseudoobscura from colombia. | there are several colombian populations of drosophila pseudoobscura which have begun to show divergence. the temporal samples of torobarroso, one of the local populations identified, demonstrate genetic "resourcefulness" and selective opportunism by fluctuating mortality. the data suggest that both balanced selection and mutational origin are necessary to account for the frequencies of drastic genes encountered. in genetic isolates there seems to exist alternatively a mutational component and a ... | 1983 | 24263539 |
| tissue localization of esterase-5 in drosophila pseudoobscura. | disc gel electrophoresis of dissected adults of drosophila pseudoobscura showed that most of the esterase-5 activity was in the head (36%) and thorax (51%), with little activity in the abdomen (13%). no activity was found in digestive tissues, reproductive tissues, or nervous tissues. most of the est-5 activity (61%) was found to be associated with hemolymph. however, the eyes contained 39% of the total est-5 activity. these results were supported by spectrophotometric assays of esterase activit ... | 1983 | 6870773 |
| origin of x/o progeny from crosses of sex-ratio trait males of drosophila pseudoobscura. | males of drosophila pseudoobscura carrying the sex-ratio chromosome (sr) were studied to determine the cause of x/o male progeny that they produce. it was found that among 3671 x/o progeny virtually all resulted from nullo-x sperm. the experiment also revealed a dramatic clustering of the frequency of x/o progeny among sr/y males. this is interpreted to indicate that premeiotic events in the male germ line are the cause of nullo-x sperm. | 2003 | 6863891 |
| population genetics of drosophila amylase. iv. selection in laboratory populations maintained on different carbohydrates. | two polymorphic systems impinging on alpha-amylase in drosophila pseudoobscura have been studied in laboratory populations maintained on medium in which the only carbohydrate source was starch (the substrate of amylase) and replicas maintained on medium in which the only carbohydrate source was maltose (the product of amylase). the two polymorphic systems were alleles at the structural gene (amy) coding for the enzyme (allozymes) and variation in the tissue-specific expression along the adult mi ... | 1983 | 6189764 |
| interspecific cytoplasmic gene flow in the absence of nuclear gene flow: evidence from drosophila. | mtdna polymorphism has been studied by restriction endonuclease site variation in drosophila pseudoobscura and its sibling species d. persimilis. eight enzymes have been used to study 54 isofemale strains from areas where the two species are sympatric and d. pseudoobscura is allopatric. where sympatric, 75-80% of the strains have mitochondrial genomes found in both species. where allopatric, d. pseudoobscura has diverged to the point where none of the strains have mtdna in common with d. persimi ... | 1983 | 6300849 |
| an experimental study of neutrality at the malic dehydrogenase and esterase-5 loci in drosophila pseudoobscura. | | 1982 | 7085337 |
| components of maze running in drosophila pseudoobscura dn drosophila persimilis. | | 1981 | 7325947 |
| gene flow and the geographical distribution of a molecular polymorphism in drosophila pseudoobscura. | this paper discusses the relation between the geographical distribution of an enzyme polymorphism and population structure in drosophila pseudoobscura. california populations of this species living in very different montane and lowland habitats separated by several kilometers are similar to each other in the frequency of an esterase allele. previous estimates suggest that gene flow is too limited to account for this homogeneity of genetic structure, so that it must reflect some balancing force o ... | 1981 | 7338302 |
| density- and frequency-dependent selection at the mdh-2 locus in drosophila pseudoobscura. | we have studied differences in the number of drosophila pseudoobscura produced in a culture when the flies differ with respect to two alleles (f and s) at the mdh-2 locus, which codes for a malate dehydrogenase enzyme. the studies were done at low and at high density in two- and three-genotype combinations (s/s, f/f and s/f), with one-genotype cultures as controls.--density affects the fitness of the mdh-2 genotypes. different genotypes are differently affected, and the genotype of the competito ... | 2017 | 7297852 |
| variation in biochemical properties of allozymes of xanthine dehydrogenase in drosophila pseudoobscura. | twenty-six d. pseudoobscura strains isogenic for xanthine dehydrogenase alleles from mesa verde, colorado, were tested for differences in the biochemical properties of different allelic forms of xanthine dehydrogenase. no significant differences in binding affinity (km) or substrate specificity of the enzyme were found. significant variation among strains, in activity (vmax) and among electromorphs, as well as among strains, in thermolability was found. for the few strains tested, the activity a ... | 1980 | 6943118 |
| photobehavioral differentiation in natural populations of drosophila: changes of photoresponse over time in drosophila pseudoobscura and drosophila persimilis. | the photobehavior of a sympatric assemblage of drosophila pseudoobscura and d. persimilis from california was examined over a 13-month period. during that time, certain aspects of the behavior remained constant (e.g., the mean resting photoresponse), while other aspects changed (e.g., the level of genotypic variation of the resting photoresponse of d. persimilis). the data support the contention of rockwell et al. [rockwell, r. f., cooke, f., and harmsen, r. (1975). behav. genet. 5:189-202] that ... | 1980 | 7469972 |
| activity variants of acid phosphatase-3 among chromosome 3 inversions of drosophila pseudoobscura. | allozymes of the ap-3 locus in drosophila pseudoobscura show very strong associations with chromosome 3 inversions. the 0.98 electrophoretic allele is associated with the tl, sc, ch and pp gene arrangements, while the 1.00 electrophoretic allele is characteristic of the ar and st gene arrangements. variation in relative 0.98 and 1.00 ap-3 allozyme activities of chromosome 3 isogenic strains was examined on acrylamide gels in f1 heterozygotes obtained by crossing these strains individually to a r ... | 1980 | 7262544 |
| distinctions among allelic variants associated with chromosome 3 inversions in drosophila pseudoobscura and drosophila persimilis. | efforts were made to discriminate new genetic variants among electrophoretic alleles that are associated with chromosome 3 inversions of drosophila pseudoobscura and d. persimilis. apparent genetic similarities for electrophoretic alleles between these two species and among the common inversions they carry were reexamined by altering gel concentration and buffer ph. at the amylase locus, the 1.09 electrophoretic allele could be further separated into two allelic classes that differentiated the w ... | 1980 | 6167488 |
| clan lethals and inter-year allelism in death valley drosophila pseudoobscura. | a chromosome 2 lethal allelism rate of about 3% found in the 1974 population of d. pseudoobscura in death valley, california. this rate was significantly higher than allelism rates in other southern california populations. the death valley population was sampled again in 1975 and 1977, with allelism rates of 1% and 0.5%, respectively. in 1974, several lethals were in high frequencies (about 1%), a pattern that reappeared in 1975 and 1977. however, none of the lethals in high frequency one year w ... | 1980 | 7203006 |
| variation in activities of amylase allozymes associated with chromosome inversions in drosophila pseudoobscura, d. persimilis and d. miranda. | different electrophoretic alleles of amylase show associations with particular chromosome 3 inversions in d. pseudoobscura and d. persimilis. relative adult amylase activities were compared in 37, 37 and 10 strains of d. pseudoobscura, d. persimilis and d. miranda, respectively. strains carrying the same electrophoretic allele were compared by crossing these lines individually to a reference strain carrying a different electrophoretic mobility allele. this procedure allows comparisons among spec ... | 1980 | 6159250 |
| composite stepwise mutation model under the neutral mutation hypothesis. | as an extension of the conventional ("ohta-kimura") stepwise mutation model, a new model is proposed. in this model, it is assumed that each charge state ("electromorph") is represented by k alleles and that a mutation changes an allele either by one step in the charge space or to one of the other members of the identical electromorph. it is shown that the net genetic variability within a population is similar to that predicted by the infinite-allele model ("kimura-crow" model) rather than to th ... | 1980 | 6928979 |
| experimental and theoretical analysis of the "sex-ratio" polymorphism in drosophila pseudoobscura. | the sex-ratio chromosome (sr) is a widespread, multiply inverted rearrangement of the x chromosome present in several species of drosophila. male carriers transmit mostly x-bearing sperm. in the absence of strong counteracting selection, sr is expected to increase rapidly to fixation, causing extinction. the present study incorporates a selection-components analysis of sr in laboratory populations, using the closely linked esterase-5 locus as a marker. estimated fitnesses show directional viabil ... | 1980 | 17249004 |
| apparent absence of a separate beta-oscillator in phasing the circadian rhythm of eclosion in drosophila pseudoobscura. | | 1980 | 7458798 |
| dosage compensation of x-linked heat-shock puffs in drosophila pseudoobscura. | four major puffs are inducible by heat shock in the larval salivary gland chromosomes of d. pseudoobscura. two of these puffs are present at 23 and 39-40 on the right arm of the x chromosome and two are present at 53 and 58 on chromosome 2. by means of in situ hybridization, residual homologies were demonstrated between the puffs at 23 in d. pseudoobscura and at 63 c in d. melanogaster, and between the two chromosome 2 puffs of d. pseudoobscura and 87a and 87c of d. melanogaster. rna synthesis w ... | 1980 | 6155244 |
| gene flow and life history patterns. | dispersal distances overestimate the gene-flow scale l (the square-root of the mean squared distance travelled from birth to reproduction) when egg laying is concentrated early in dispersal and when there is mortality during dispersal. if egg laying follows a square-root normal distribution in time, as it does in several drosophila species, then l is reduced to about 0.6 of that estimated from dispersal alone, unless egg laying is concentrated in a very brief period. if mortality is such that th ... | 1979 | 17248966 |
| frequency-dependent selection at the pgm-1 locus of drosophila pseudoobscura. | frequency-dependent fitness was studied at the pgm-1 locus of drosophila pseudoobscura with respect to two fitness components: rate of development and larva-to-adult survival. the pgm-1 locus is very polymorphic with only two alleles, pgm-1(100) and pgm-1(104), occurring at high frequencies. for each of these two alleles, 20 homozygous strains were obtained from a sample of 1,140 wild-inseminated females. first-instar larvae of the two genotypes were combined in a set of eight different frequenc ... | 1979 | 161241 |
| population genetics of drosophila amylase. ii. geographic patterns in d. pseudoobscura. | morph frequencies of three related polymorphisms were determined in ten natural populations of drosophila pseudoobscura. they are the well-known inversion polymorphism of the third chromosome and the polymorphism for alpha-amylase produced by the structural gene amy (which resides on the third chromosome). the third polymorphism was for tissue-specific expression of amy in adult midguts; a total of 13 different patterns of activity have been observed. the preceding paper (powell and lichtenfels ... | 1979 | 488707 |
| population genetics of drosophila amylase. i. genetic control of tissue-specific expression in d. pseudoobscura. | drosophila pseudoobscura is polymorphic for tissue-specific expression of alpha-amylase in adult midguts. this enzyme is encoded by a single locus, amy, on the third chromosome. in this paper we show: (1) up to about 12 days post-eclosion, the midgut activity patterns remain stable; after 12 days areas not showing activity previously begin to show activity. thus, the genes controlling the expression of amy are temporally acting. (2) diet affects the quantitative, but not the qualitative, express ... | 1979 | 488706 |
| evidence for selection by male mating success in natural populations of drosophila pseudoobscura. | gene arrangement frequencies were determined at two stages in the life history of drosophila pseudoobscura taken from nature. three populations in the central highlands of mexico were each sampled twice during 1976. gene arrangement frequencies were measured in adult males and in larvae that were the offspring of females collected at the same time. the adult males were in all likelihood a representative sample of those who fathered the larvae produced by the wild females. differences in gene arr ... | 1979 | 286338 |
| extent of genetic variation at a highly polymorphic esterase locus in drosophila pseudoobscura. | the esterase-5 locus of drosophila pseudoobscura has been screened for variation by using a wide variety of electrophoretic conditions and by testing heat sensitivity. among 50 isogenic lines from 17 populations, 21 genetic variants were found at the locus, 18 by electrophoresis and 3 by heat denaturation. including alleles previously known, there are a total of 30 alleles at this locus in natural populations. this represents a doubling of the previous estimates of polymorphism at this locus. th ... | 1978 | 283418 |
| study of the charge-state model for electrophoretic variation using isoelectric focusing of esterase-5 from drosophila pseudoobscura. | | 1978 | 683345 |
| response to selection for mating speed and changes in gene arrangement frequencies in descendants from a single population of drosophila pseudoobscura. | heritability estimates, based on 19 generations of selection for fast and slow mating speed, were not significantly different from zero at the 0.05 level in any replicate of selected lines in a population of flies descended from the mather population in california. only the combined heritability estimate of approximately 2% was significant. this indicated that very little additive genetic variance was present in the base population and that strong directional selection for rapid mating may have ... | 1978 | 17248849 |
| gene frequencies of an isolated population of drosophila pseudoobscura. | allozyme and karyotype frequencies were determined for an isolated population of drosophila pseudoobscura on san miguel island off the california coast. this population was not very different from that of the mainland, and seems to indicate that isolation does not necessarily lead to genetic differentiation. | 2003 | 731008 |
| positive and negative geotaxis: sex-linked traits in drosophila pseudoobscura. | using a hirsch classification maze, selection was made for positive and negative geotactic behaviors in three different strains of drosophila pseudoobscura. hybridization studies were then carried out with flies from the diverged strains. the geotactic scores of the parents and f1 flies indicate that both negative and positive geotactic behaviors in these strains are strongly influenced by genes in the x chromosome. additional hybridization studies using flies from strains with similar phenotype ... | 1978 | 565202 |
| examination of allelic variation at the hexokinase loci of drosophila pseudoobscura and d. persimilis by different methods. | recently a number of electrophoretic techniques have been applied to reveal the presence of additional genetic variation among the electrophoretic mobility classes of the highly polymorphic xanthine dehydrogenase (xdh ) and esterase-5 (est-5) loci. we examined the hexokinase loci of drosophila pseudoobscura and d. persimilis using a variety of techniques to determine whether further allelic variation could be revealed for these much less polymorphic loci and to analyze the nature of the known va ... | 1977 | 17248785 |
| an experimental investigation of the unit charge model of protein polymorphism and its relation to the esterase-5 locus of drosophila pseudoobscura, drosophila persimilis, and drosophila miranda. | the relationship between charge changes and electrophoretic mobility changes is investigated experimentally. the charge of several proteins is altered by reaction with small molecules of known structure and the change in electrophoretic mobility is measured. the method of ferguson plots is used to separate charge and shape components of mobility differences. the average effect of an amino acid charge change on the mobility of the esterase-5( 1.00) allele of drosophila pseudoobscura is estimated ... | 1977 | 17248784 |
| a test for rare male mating advantage at an "enzyme locus" in drosophila. | matings between drosophila pseudoobscura strains differing at the amylase (amy) locus were observed in elens-wattiaux chambers. males homozygous for either amy1.00 or amy0.84 alleles in the ch gene arrangement enjoyed a mating advantage when moderately rare, but none when quite rare. the minority male advantage for strains differing at the amy locus, and other loci linked to it, was comparable in size to that observed between strains carrying the st or ch gene arrangements, and either alike or d ... | 1977 | 603476 |
| drift or selection: a statistical test of gene frequency variation over generations. | the method used by fisher and ford (1947) to study the spread of a gene in a natural population has been modified to analyze the variation in allele frequencies from generation to generation in a common experimental procedure. a further analysis has been developed that is more sensitive to directional trends in the allele frequency over generations, and its use in detecting the action of directional selection on gene frequency at a locus is discussed. the power of each of these statistical tests ... | 1977 | 17248769 |
| gene frequency changes at the alpha-amylase locus in experimental populations of drosophila pseudoobscura. | the frequencies of alleles at the alpha-amylase locus of d. pseudoobscura were followed in both large and small experimental populations. no evidence for balancing or directional selection was found, although our ability to detect weak selection is limited. the gene frequency changes in our experimental populations were consistent with the hypothesis of selective neutrality and genetic drift due to sampling error. | 1977 | 17248768 |
| genic heterogeneity at two alcohol dehydrogenase loci in drosophila pseudoobscura and drosophila persimilis. | a sequential electrophoretic survey of the second chromosome loci, alcohol dehydrogenase-6 (adh-6) and octanol dehydrogenase ( odh), was performed on 147 isochromosomal lines of drosophila pseudoobscura and 60 lines of its sibling species, d. persimilis. gels run with a variety of acrylamide concentrations and buffer ph's revealed the presence of 18 alleles of adh-6 in the two species, where only eight had been previously detected by conventional electrophoretic methods. only two alleles were ad ... | 1977 | 17248763 |
| allelic variants at the xanthine dehydrogenase locus affecting enzyme activity in drosophila pseudoobscura. | quantitative studies of enzyme activity on gels show about four-fold differences in enzyme activity of different xanthine dehydrogenase (xdh ) alleles. at least three different activity classes could be distinguished among the 23 strains isogenic for the xdh locus. no association of high activity with the high frequency electromorph was observed; instead, the low frequency electromorphs had 0.5 to 2 times the activity of the high frequency electromorph. the frequency of low activity, high activi ... | 1977 | 17248755 |
| evaluation of the stepwise mutation model of electrophoretic mobility: comparison of the gel sieving behavior of alleles at the esterase-5 locus of drosophila pseudoobscura. | seven alleles at the esterase-5 locus of drosophila pseudoobscura appear approximately uniformly spaced on 5% acrylamide gels. such stepwise "ladders" in mobility have been used to argue for the charge-state model of electrophoretic mobility. to evaluate this interpretation, flies of the seven strains were examined in replicate electrophoresis on polyacrylamide gels of differing pore size, permitting estimation of the relative contributions of charge and of size/conformation to electrophoretic m ... | 1977 | 17248754 |
| a comparative study of the esterase-5 locus in drosophila pseudoobscura, d. persimilis and d. miranda. | electrophoretic phenotypes of the esterase-5 locus were examined in the sibling species d. pseudoobscura, d. persimilis and d. miranda. d. persimilis alleles were found to have uniformly higher charge on monomers than corresponding alleles of either d. pseudoobscura or d. miranda. consequently, d. persimilis shares no alleles in common with either d. pseudoobscura or d. miranda, while the latter two species share a number of alleles. it was discovered that by increasing the concentration of acry ... | 1977 | 863241 |
| gene differences between the sex ratio and standard gene arrangements of the x chromosome in drosophila persimilis. | the sibling species drosophila pseudoobscura and d. persimilis each carry two gene arrangements in the right arm of the x chromosome; standard (st) and sex ratio (sr). the sr sequence of d. persimilis and the st sequence of d. pseudoobscura have the same banding pattern. these cytologically identical arrangements carry different alleles at the esterase-5 (est-5) and phosphoglucomutase-1 ( pgm-1) loci. all the alleles on the sr arrangement of d. persimilis are also present on the st arrangement o ... | 1977 | 17248742 |
| chromosomal and allozymic diagnosis of three species of drosophila. drosophila pseudoobscura, d. persimilis, and d. miranda. | techniques are presented for distinguishing the sibling species d. pseudoobscura, d. persimilis, and d. miranda in two ways: by differences in the banding sequence of salivary chromosomes, and by the frequencies of allozymes at certain diagnostic loci. | 2009 | 874309 |
| the frequency and allelism of lethal chromosomes in isolated desert populations of drosophila pseudoobscura. | second-chromosome lethals were extracted from four populations of drosophila pseudoobscura in southern california. two of the populations were from desert oases and two from the classic habitat on mt. san jacinto, previously studied by dobzhansky. allelism tests were made on the lethals within and between all locations. the frequency of lethal second-chromosomes in each location was 0.18, and this was not different from the results of other workers for samples throughout the species range. inter ... | 1976 | 1010313 |
| allelic heterogeneity within allozymes separated by electrophoresis in drosophila pseudoobscura. | electrophoretic separation of esterase-5 allozymes of drosophila pseudoobscura in gels of different acrylamide concentrations and in different buffer systems has revealed the existence of six different alleles within the most frequent class, esterase-5(1.00), and three alleles in the other most frequent class, esterase-5(1.07). two of the alleles affect subunit binding. esterase-5 allozyme classes based on electrophoresis in 5% acrylamide gels are therefore highly heterogeneous. | 1976 | 1069304 |
| genetic heterogeneity within electrophoretic "alleles" of xanthine dehydrogenase in drosophila pseudoobscura. | an experimental plan for an exhaustive determination of genic variation at structural gene loci is presented. in the initial steps of this program, 146 isochromosomal lines from 12 geographic populations of d. pseudoobscura were examined for allelic variation of xanthine dehydrogenase by the serial use of 4 different electrophoretic conditions and a head stability test. the 5 criteria revealed a total of 37 allelic classes out of the 146 genomes examined where only 6 had been previously revealed ... | 1976 | 1001881 |
| recongition and sexual selection in drosophila: classification, quantification, and identification. | drosophila pseudoobscura females show a positive bias toward mating with males whose proportion in the population is low. they can perform this discrimination even when three strains of males are present. the olfactory recognition required for this discrimination entails a hierarchically ordered recognition system and a natural unit of olfactory strength. | 1976 | 948745 |
| homeostatic drive counteracting selection for positive and negative phototaxis and geotaxis in drosophila pseudoobscura. | tested in hirsch-hadler mazes, drosophila pseudoobscura is on the average geoneutral and photoneutral. strongly geo- and photopositive and geo- and photonegative populations can be obtained by artificial selection, but upon relaxation of the selection they tend to relapse toward neutrality. this genetic homeostasis is due to natural selection favoring neutrality. experiments are described in which artificial selection for positivity and for negativity was deliberately made so weak that it only c ... | 1976 | 973830 |
| genetics of natural populations, xliii. further studies on rates of dispersal of drosophila pseudoobscura and its relatives. | the amount of gene flow among local populations of a species is determined by the dispersal capacity of that species. population samples of drosophila pseudoobscura, d. persimilis, d. azteca, and d. miranda were collected, marked with ultraviolet fluorescent dusts, and released as soon as possible after capture. one and two days after release, recaptures were made on baits placed at 40-meter intervals in straight lines intersecting the release point. on alternative days, the baits were placed in ... | 1976 | 1269906 |
| substrate-specific enzyme variation in natural populations of drosophila pseudoobscura. | by using a number of different alcohols as substrates, eight alcohol dehydrogenase loci were discovered in drosophila pseudoobscura. each of these loci can take more than one substrate. several of these loci differed in their tissue specificities and activity patterns during development. the genic variation in natural populations was studied at four of these loci and three of them were polymorphic. a quantitative study of substrate-specific differences among alleles of the same locus produced ne ... | 1976 | 773744 |
| hyperactivity and faster replicating property of the two arms of the male x of drosophila pseudoobscura. | the two arms of the x chromosome of drosophila pseudoobscura have different phylogenetic origin, the xl being homologous to the x and the xr homologous to the 3l of d. melanogaster. the replicative and transcriptive activities of the two arms have been examined in order to understand how such phylogenetically different components of the x contribute toward the chromosomal basis of dosage compensation. the 3h-uridine labelled autoradiograms of the polytene chromosomes of larval salivary glands re ... | 1976 | 946831 |
| interchromosomal asynchrony of dna replication in polytene chromosomes of drosophila pseudoobscura. | analysis of 3h-thymidine autoradiograms of late third instar larval salivary glands of drosophila pseudoobscura revealed a unique example of asynchrony of replication in the autosome complement. the two autosomal arms, 2 and 3, show similar labeling pattern during the initial phases, dd to 3c, and thereafter, the chromosome 3 has fewer labeled sites than chromosome 2 until the most terminal pattern, 1d. detailed sitewise analysis of 3h-thymidine labeling shows that while nearly 54% of the sites ... | 1976 | 1248337 |
| polymorphism for dimerizing ability at the esterase-5 locus in drosophila pseudoobscura. | three new alleles are reported at the esterase-5 locus of drosophila pseudoobscura. all three of these alleles are different from those previously reported in their ability to dimerize. one allele will not form heterodimers or homodimers and exists only as a monomer. a second allele does form heterodimers but will not form homodimers. the third allele forms both hetero- and homodimers as well as forming monomers. estimates of the frequency of these alleles in a natural population are given. the ... | 1976 | 1248736 |
| chromosomal basis of dosage compensation in drosophila viii. faster replication and hyperactivity of both arms of the x-chromosome in males of drosophila pseudoobscura and their possible significance. | 3h-thymidine and 3h-uridine labeling patterns of the x-chromosome arms of drosophila pseudoobscura have been examined autoradiographically. results show that in all phases of replication, namely, initial, middle and terminal, both arms of the x-chromosome in the male are advanced by one or two steps of 3h-thymidine labeling in comparison with the autosomes, and both arms in the female show more or less similar labeling profile as the autosomes. both the arms in the male show pale stainability an ... | 1975 | 1201689 |
| distribution among the chromosomes of drosophila pseudoobscura of the genes governing the response to light. | most strains of drosophila pseudoobscura are neutral to light when tested in phototactic mazes. however, clear-cut photopositive and photogenative populations are obtained by selection over a series of generations. the genetic nature of the differences between the positive and negative populations has been studied in crosses in which the three large autosomes carried mutant markers. all chromosomes contain genes which influence the response to light. the third chromosome has the strongest effect ... | 1975 | 1205129 |
| dna replication in polytene chromosomes of drosophila pseudoobscura: new facts & their implications. | | 1975 | 1218903 |
| photobehavioral differentiation in natural populations of drosophila pseudoobscura and drosophila persimilis. | the photoresponses of natural populations of d. pseudoobscura and d. persimilis, occurring sympatrically, are measured in two environmental conditions ("at rest" and "disturbed"). comparisons of the responses, intraspecifically and interspecifically, lead to the following conclusions. these must be considered within the confines of the operational nature of the measurement of laboratory photoresponses. (1) within each species population, significant nonenvironmental differentiation has been allo ... | 1975 | 1131147 |
| a biometrical analysis of a mating characteristic in drosophilia. | a model is described for the biometrical analysis of interaction behavioural characteristics. the model is illustrated by analysis of the mating speed of drosophila pseudoobscura derived from crosses of fast and of slow mating strains generated through artificial selection. | 1975 | 1054670 |
| fitness of allozyme variants in drosophila pseudoobscura. i. selection at the pgm-1 and me-2 loci. | we have studied in drosophila pseudoobscura the effect of allozyme variation on seven fitness components: female fecundity, egg hatchability, egg-to-adult survival under near-optimal and under competitive conditions, rate of development under near-optimal and under competitive conditions, and mating capacity of males. three genotypes at each of two loci, pgm-1 and me-2, have been studied in various combinations. these two loci are highly polymorphic in natural populations of d. pseudoobscura. st ... | 1975 | 1126623 |
| further evidence for selective differences between isoalleles in drosophila. | a number of separate strains of drosophila pseudoobscura were inbred for 38 generations of brother-sister mating with forced heterozygosity for two alleles of either the octanol dehydrogenase or esterase-5 locus. crosses were set up within each of these inbred lines such that simple mendelian ratios were expected, and eggs from these crosses were placed on media with additions simple chemicals likely to interact with alleles of the two loci--octanol and ethanol for the odh locus and tributyrin a ... | 1975 | 1126619 |
| fitness of karyotypes in drosophila pseudoobscura. | in the dynamics of the survival of chromosomal polymorphism selection may be operating at the genic level, at the chromosomal level or at the supergene level. tests designed to distinguish between these levels were run on drosophila pseudoobscura. there was no evidence for heterosis, a necessary requirement for gene-determined chromosomal polymorphism a strong chromosmal selection was observed. no evidence was found for the presence within one locality of more than a single superallele for each ... | 1975 | 1126618 |
| dosage compensation of genes on the left and right arms of the x chromosome of drosophila pseudoobscura and drosophila willistoni. | we have investigated the occurrence of dosage compensation in d. willistoni and d. pseudoobscura, two species whose x chromosome is metacentric with one arm homologous to the x and the other homologous to the left arm of chromosome 3 of d. melanogaster. crude extracts were assayed for isocitrate dehydrogenase (xr), glucose-6-phosphate dehydrogenase (xl?), 6-phosphogluconate dehydrogenase (xl?), and alpha-glycerophosphate dehydrogenase (chromosome 2) in d. willistoni, and for esterase-5 (xr), glu ... | 1974 | 4455556 |
| genetic background and the fitness of allozymes. | experimental perturbations of gene frequency at the esterase-5 locus in drosophila pseudoobscura were carried out in a series of population cages started with differing numbers of founder chromosomes. cages founded with few chromosomes showed changes in gene frequency at the allozyme locus. such changes were less marked in cages founded with a larger sample of chromosomes. these experiments show the importance of linkage disequilibrium in affecting allozyme frequencies, and emphasize the necessi ... | 1974 | 4455555 |
| esterases of drosophila. ii. biochemical studies of esterase-5 in d. pseudoobscura. | in vitro enzyme hybridization was carried out with combinations of six allozymic variants of esterase-5 from drosophila pseudoobscura. studies on heat stability and specific activity changes accompanying hybridization were done to examine the possible expression of overdominance at the biochemical level. in 11 of 15 combinations no significant change in specific activity was found following hybridization. in two cases hybridization resulted in a decrease in activity in the mixture, while in two ... | 1974 | 4455554 |
| rates of dispersal of drosophila pseudoobscura and its relatives. | | 1974 | 4154451 |
| fitness of allozyme variants in drosophila pseudoobscura. ii. selection at the est-5, odh and mdh-2 loci. | | 1974 | 4452479 |
| light dependence in matings of drosophila pseudoobscura. | | 1974 | 4414479 |
| gene differences between the sex ratio and standard gene arrangements of the x chromosome and linkage disequilibrium between loci in the standard gene drosophila pseudoobscura. | the standard and sex ratio gene arrangements of the x chromosome of d. pseudobscura differ from each other in allele frequencies at the four x chromosome loci, esterase-5, adult acid phosphatase-6, phosphoglucomutase-1 and octanol dehydrogenase-3. the standard arrangement which is the common arrangement in all populations is polymorphic at these loci in varying degrees, the geographically less widespread sex ratio arrangement has little polymorphism and is genically predominantly e-5(1.04) ap-6( ... | 1974 | 4417060 |
| selection by fertility in drosophila pseudoobscura. | fertility, the component of selection due to female fecundity and male mating success, differed significantly among the st/st, st/ar, and ar/ar karyotypes in experimental populations and varied with karyotypic frequency. in relation to st/ar, st/st females and males had higher fertilities at low frequency; ar/ar males and females were at a significant fertility disadvantage at intermediate frequency, while at low and at high frequencies their fertilities matched or exceeded that of the heterokar ... | 1974 | 4426507 |