scholarly journals Distinguishing the forces controlling genetic variation at the Xdh locus in Drosophila pseudoobscura.

Genetics ◽  
1989 ◽  
Vol 123 (2) ◽  
pp. 359-369 ◽  
Author(s):  
M A Riley ◽  
M E Hallas ◽  
R C Lewontin
Keyword(s):  
Genetic Variation ◽  
Linkage Disequilibrium ◽  
Base Pair ◽  
Natural Populations ◽  
Xanthine Dehydrogenase ◽  
Drosophila Pseudoobscura ◽  
Common Haplotype ◽  
Coding Region ◽  
Data Set ◽  
Restriction Sites

Abstract Fifty-eight isochromosomal lines sampled from two natural populations of Drosophila pseudoobscura in California and one from Bogota, Colombia, were examined using four-cutter restriction mapping. A 4.6-kb region of the xanthine dehydrogenase locus was probed and 66 of 135 restriction sites scored were polymorphic. This predicts that on average every 12th bp would be polymorphic in this region for the genes surveyed if polymorphism occurred randomly along the coding region. In addition, there were 12 insertion/deletion polymorphisms. Forty-nine distinct haplotypes were recognized in the 58 lines examined. The most common haplotype obtained a frequency of only 5%. Measures of base pair heterozygosity (0.0097) and linkage disequilibrium lead to a predicted population size in the range of 1.2-2.4 X 10(6) for the species. High levels of recombination (including gene conversion) can be inferred from the presence of all four gametic types in the data set.

scholarly journals Recent evolutionary history of the metallothionein gene Mtn in Drosophila

1991 ◽  
Vol 58 (3) ◽  
pp. 203-210 ◽  
Author(s):  
Laurent Theodore ◽  
Ann-Shu Ho ◽  
Gustavo Maroni
Keyword(s):  
Base Pair ◽  
Restriction Analysis ◽  
Natural Populations ◽  
Fold Increase ◽  
Coding Region ◽  
Tropical Africa ◽  
African Populations ◽  
History Of ◽  
Rna Accumulation ◽  
Abundant Transcript

SummaryA new allele of one of the metallothionein genes of D. melanogaster, Mtn•3, sheds light on the recent evolution of this gene. In comparison to the previously studied Mtnl allele found in Canton S, this new allele, Mtn•3, produces a transcript that is 49 bases longer and 65–70 % less abundant. We detected Mtn•3 in several laboratory strains as well as in isofemale lines derived from natural populations. Sequence comparison showed that Mtn•3 differs from Mtnl in that it has: (a) base-pair substitution and an extra 49 bp-segment in the 3' untranslated region, (b) a substitution in the coding region that replaces the terminal Glu40 in Mtnl with Lys40, and (c) two base-pair substitutions in the promoter region. The Mtn•3-type was detected in six species of the melanogaster group by restriction analysis, and this result was confirmed by sequencing the D. simulans Mtn gene. Thus Mtn•3, which produces a less abundant transcript, appears to be the oldest of the two alleles. We also found that the duplications previously isolated from natural populations all derived from Mtnl, the more recent allele. Thus, two evolutionary steps: Mtn•3 to Mtnl and Mtnl to Dp(Mtnl), are accompanied by an overall 5- to 6-fold increase of RNA accumulation. The two changes seem to have occurred in non-African populations since Mtn•3 but not Mtnl was detected in our sample from tropical Africa, while Mtnl and Dp (Mtnl) are prevalent in European and North American samples.

scholarly journals GENIC HETEROGENEITY WITHIN ELECTROPHORETIC "ALLELES" AND THE PATTERN OF VARIATION AMONG LOCI IN DROSOPHILA PSEUDOOBSCURA

Genetics ◽  
1979 ◽  
Vol 93 (4) ◽  
pp. 997-1018
Author(s):  
Rama S Singh
Keyword(s):  
Balancing Selection ◽  
Natural Populations ◽  
Aldehyde Oxidase ◽  
Xanthine Dehydrogenase ◽  
Drosophila Pseudoobscura ◽  
Mainland Population ◽  
Polymorphic Loci ◽  
Genic Variation ◽  
Pattern Of Variation

ABSTRACT An investigation, similar to our previously reported xanthine dehydrogenase study, was undertaken to examine the extent of hidden genic variation at nine loci (five larval proteins, three esterases and one aldehyde oxidase) by sequential application of various electrophoretic criteria employing pH, gel concentration and buffer variation. Polymorphic loci appear to fall into two distinct groups: weakly polymorphic, including larval protein 6, 7, 8, 10 and 13 and esterase-1 and -6; and highly polymorphic, including esterase-5, Xdh and possibly Ao. Monomorphic loci may belong to a third group different from all polymorphic lori. Bogota, a geographical isolate that is reproductively isolated from the mainland population, was found to be genetically distinct at four of the ten loci examined in detail so far, including Xdh, whereas previously it was found to be genetically distinct at none. These results are discussed in the light of balancing selection, neutral and mutation-selection hypotheses of genic variation in natural populations.

scholarly journals LINKAGE DISEQUILIBRIUM IN NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER

Genetics ◽  
1974 ◽  
Vol 78 (3) ◽  
pp. 921-936
Author(s):  
Charles H Langley ◽  
Yoshiko N Tobari ◽  
Ken-Ichi Kojima
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Linkage Disequilibrium ◽  
Natural Populations ◽  
Chromosomal Gene ◽  
Gene Frequencies ◽  
Linkage Disequilibria ◽  
Allozyme Loci ◽  
Two Populations ◽  
Stable Populations

ABSTRACT Two large, stable populations (Texas and Japan) of Drosophila melanogaster were surveyed at 21 allozyme loci on the second and third chromosomes and for chromosomal gene arrangements on those two chromosomes. Over 220 independent gametes were sampled from each population. The types and frequencies of the surveyed genetic variation are similar to those observed previously and suggest only slight differentiation among geographically distant populations. Linkage disequilibrium among linked allozymes loci is only slightly, if at all, detectable with these sample sizes. Linkage disequilibrium between linked inversions and allozymes loci is common especially when located in the same arm. These disequilibria appear to be in the same direction for most comparisons in the two population samples. This result is interpreted as evidence of similar selective environments (ecological and genetic) in the two populations. It is also noted that the direction of these linkage disequilibria appears to be oriented with respect to the gene frequencies at the component loci.

scholarly journals EVIDENCE FOR LINKAGE DISEQUILIBRIUM MAINTAINED BY SELECTION IN TWO NATURAL POPULATIONS OF DROSOPHILA SUBOBSCURA

Genetics ◽  
1973 ◽  
Vol 73 (4) ◽  
pp. 659-674
Author(s):  
E Zouros ◽  
C B Krimbas
Keyword(s):  
Linkage Disequilibrium ◽  
Natural Populations ◽  
Low Frequency ◽  
Aldehyde Oxidase ◽  
Xanthine Dehydrogenase ◽  
Drosophila Subobscura ◽  
Random Drift ◽  
Mainland Population ◽  
Lines Of Evidence

ABSTRACT One island and one mainland population of Drosophila subobscura were found polymorphic at the XDH (xanthine dehydrogenase) and the A0 (aldehyde oxidase) loci. It was observed that one allele at the XDH locus, which has a low frequency in both populations, is nonrandomly associated with the alleles at the A0 locus. Two lines of evidence support the thesis that this linkage disequilibrium is due to epistasis rather than random drift: (I)D or r, measures of the disequilibrium, have the same sign and magnitude in both populations. (2) The linkage disequilibrium is not due to inversions. Inversions segregating on the chromosome carrying XDH and A0 have been separated into two classes, between which exchange of alleles at the two loci is suppressed. Linkage disequilibrium for XDH and A0 was observed within each class. In the absence of any exchange of alleles, these disequilibria must have arisen and been maintained independently. The suggestion is made that the epistatic disequilibrium results from the close structural and physiological relationship which exists between the tn-o enzymes.

scholarly journals VARIATION IN BIOCHEMICAL PROPERTIES OF ALLOZYMES OF XANTHINE DEHYDROGENASE IN DROSOPHILA PSEUDOOBSCURA

Genetics ◽  
1980 ◽  
Vol 96 (4) ◽  
pp. 927-938
Author(s):  
David R Wilcox ◽  
Satya Prakash
Keyword(s):  
Substrate Specificity ◽  
Binding Affinity ◽  
Electrophoretic Mobility ◽  
Significant Variation ◽  
Xanthine Dehydrogenase ◽  
Biochemical Properties ◽  
Variant Allele ◽  
Drosophila Pseudoobscura ◽  
Mesa Verde

ABSTRACT 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 (V  max) and among electromorphs, as well as among strains, in thermolability was found. For the few strains tested, the activity and thermolability differences were shown to co-segregate with the electrophoretic mobility of the variant allele.

scholarly journals POPULATION GENETICS OF ALLOZYME VARIATION IN NEUROSPORA INTERMEDIA

Genetics ◽  
1975 ◽  
Vol 80 (4) ◽  
pp. 785-805
Author(s):  
P T Spieth
Keyword(s):  
Genetic Variation ◽  
Vegetative Reproduction ◽  
Vascular Plant ◽  
Natural Populations ◽  
Allozyme Variation ◽  
Regular Feature ◽  
Local Populations ◽  
Neurospora Intermedia ◽  
Pattern Of Variation ◽  
High Level

ABSTRACT Electrophoretically detectable variation in the fungus Neurospora intermedia has been surveyed among isolates from natural populations in Malaya, Papua, Australia and Florida. The principal result is a pattern of genetic variation within and between populations that is qualitatively no different than the well documented patterns for Drosophila and humans. In particular, there is a high level of genetic variation, the majority of which occurs at the level of local populations. Evidence is presented which argues that N. intermedia has a population structure analogous to that of an annual vascular plant with a high level of vegetative reproduction. Sexual reproduction appears to be a regular feature in the biology of the species. Substantial heterokaryon function seems unlikely in natural populations of N. intermedia. Theoretical considerations concerning the mechanisms underlying the observed pattern of variation most likely should be consistent with haploid selection theory. The implications of this constraint upon the theory are discussed in detail, leading to the presentation of a model based upon the concept of environmental heterogeneity. The essence of the model, which is equally applicable to haploid and diploid situations, is a shifting distribution of multiple adaptive niches among local populations such that a given population has a small net selective pressure in favor of one allele or another, depending upon its particular distribution of niches. Gene flow among neighboring populations with differing net selective pressures is postulated as the principal factor underlying intrapopulational allozyme variation.

Protein Variation in ADH and ADH-RELATED in Drosophila pseudoobscura: Linkage Disequilibrium Between Single Nucleotide Polymorphisms and Protein Alleles

Genetics ◽  
2001 ◽  
Vol 159 (2) ◽  
pp. 673-687
Author(s):  
Stephen W Schaeffer ◽  
C Scott Walthour ◽  
Donna M Toleno ◽  
Anna T Olek ◽  
Ellen L Miller
Keyword(s):  
Linkage Disequilibrium ◽  
Single Nucleotide Polymorphisms ◽  
Drosophila Pseudoobscura ◽  
Linkage Disequilibrium Mapping ◽  
Nucleotide Polymorphisms ◽  
Neutral Model ◽  
Significant Linkage Disequilibrium ◽  
Single Nucleotide ◽  
Synonymous Sites ◽  
Significant Linkage

Abstract 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 equilibrium neutral model. The populations fail to show significant geographic differentiation of the Adh-related haplotypes. Eight of 404 single nucleotide polymorphisms (SNPs) in the Adh region were in significant linkage disequilibrium with three ADHR protein alleles. Coalescent simulations with and without recombination were used to derive the expected levels of significant linkage disequilibrium between SNPs and 18 protein haplotypes. Maximum levels of linkage disequilibrium are expected for protein alleles at moderate frequencies. In coalescent models without recombination, linkage disequilibrium decays between SNPs and high frequency haplotypes because common alleles mutate to haplotypes that are rare or that reach moderate frequency. The implication of this study is that linkage disequilibrium mapping has the highest probability of success with disease-causing alleles at frequencies of 10%.

scholarly journals Inferring Linkage Disequilibrium Between a Polymorphic Marker Locus and a Trait Locus in Natural Populations

Genetics ◽  
2000 ◽  
Vol 156 (1) ◽  
pp. 457-467 ◽  
Author(s):  
Z W Luo ◽  
S H Tao ◽  
Z-B Zeng
Keyword(s):  
Linkage Disequilibrium ◽  
Allele Frequency ◽  
Random Mating ◽  
Natural Populations ◽  
Polymorphic Marker ◽  
Marker Locus ◽  
Model Parameters ◽  
Phenotypic Variance ◽  
Wide Range ◽  
Trait Locus

Abstract Three approaches are proposed in this study for detecting or estimating linkage disequilibrium between a polymorphic marker locus and a locus affecting quantitative genetic variation using the sample from random mating populations. It is shown that the disequilibrium over a wide range of circumstances may be detected with a power of 80% by using phenotypic records and marker genotypes of a few hundred individuals. Comparison of ANOVA and regression methods in this article to the transmission disequilibrium test (TDT) shows that, given the genetic variance explained by the trait locus, the power of TDT depends on the trait allele frequency, whereas the power of ANOVA and regression analyses is relatively independent from the allelic frequency. The TDT method is more powerful when the trait allele frequency is low, but much less powerful when it is high. The likelihood analysis provides reliable estimation of the model parameters when the QTL variance is at least 10% of the phenotypic variance and the sample size of a few hundred is used. Potential use of these estimates in mapping the trait locus is also discussed.

scholarly journals Female Genotypes Affect Sperm Displacement in Drosophila

Genetics ◽  
1998 ◽  
Vol 149 (3) ◽  
pp. 1487-1493 ◽  
Author(s):  
Andrew G Clark ◽  
David J Begun
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Natural Populations ◽  
Isogenic Line ◽  
Female Fitness ◽  
Sperm Displacement ◽  
Extensive Variation ◽  
Polymorphic Genes ◽  
Displacement Parameter ◽  
Competitive Success

Abstract Differential success of sperm is likely to be an important component of fitness. Extensive variation among male genotypes in competitive success of sperm in multiply mated females has been documented for Drosophila melanogaster. However, virtually all previous studies considered the female to be a passive vessel. Nevertheless, under certain conditions female fitness could be determined by her role in mediating use of sperm from multiple males. Here we ask whether females differ among genotypes in their tendency to exhibit last-male precedence. Competition of sperm from two tester male genotypes (bwD and B3-09, a third-chromosome isogenic line from Beltsville, MD) was quantified by doubly mating female lines that had been rendered homozygous for X, second, or third chromosomes isolated from natural populations. The composite sperm displacement parameter, P2′, was highly heterogeneous among lines, whether or not viability effects were compensated, implying the presence of polymorphic genes affecting access of sperm to eggs. Genetic variation of this type is completely neutral in the absence of pleiotropy or interaction between variation in the two sexes.

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