scholarly journals Enzyme Polymorphism and Species Discrimination in Fruit Flies of the Genus Dacus (Tephritidae)

1975 ◽  
Vol 28 (4) ◽  
pp. 405 ◽  
Author(s):  
Stephen W McKechnie
Keyword(s):  
Alcohol Dehydrogenase ◽  
Small Proportion ◽  
Natural Populations ◽  
Enzyme Polymorphism ◽  
Eastern Coast ◽  
Species Discrimination ◽  
Gene Frequencies ◽  
Sympatric Populations ◽  
Hybrid Identification ◽  
Octanol Dehydrogenase

Sympatric populations of D. tryoni and D. neohumeralis are difficult to completely distinguish taxonomically. Using five pigmentation characters, each of some taxonomic value, a small proportion of individuals cannot be assigned to either species nor definitely classified as hybrids. To aid in species discrimination and hybrid identification gene frequencies in natural populations were estimated at three polymorphic protein loci, an alcohol dehydrogenase (Adh), an octanol dehydrogenase (Odh) and an esterase (E-2). Samples of flies were taken from four sites spread over 1200 miles along the Australian eastern coast.

An Ecological Study of the Alcohol Dehydrogenase (Adh) Polymorphism of Drosophila Melanogaster.

1980 ◽  
Vol 28 (6) ◽  
pp. 709 ◽  
Author(s):  
JA Mckenzie
Keyword(s):  
Drosophila Melanogaster ◽  
Ecological Study ◽  
Natural Populations ◽  
Random Processes ◽  
Enzyme Polymorphism ◽  
Quiescent State ◽  
Ecological Data ◽  
Gene Frequencies ◽  
Similar Gene ◽  
Selective Effects

Fluctuations in the numbers of adults of Drosophila melanogaster Mg. in the cellar of a vineyard in Victoria, Australia, were monitored for 5 years. Numbers fluctuated cyclically, from 50 at the end of winter to 100 000 immediately after harvest. Movement within the cellar system was restricted, especially in winter, leading to subpopulations being formed. Overwintering individuals were in a non-breeding quiescent state. These ecological conditions provide considerable potential for random processes. However, such effects did not seem of importance in the maintenance of the Adh polymorphism since concurrent samples in different areas of the cellar had similar gene frequencies, and similar genotypic distributions were observed from year to year in the cellar system as a whole. The relevance of ecological data in distinguishing between random and selective effects acting on enzyme polymorphism in natural populations is emphasised.

scholarly journals GENETIC AND BIOCHEMICAL BASIS OF ENZYME ACTIVITY VARIATION IN NATURAL POPULATIONS. I. ALCOHOL DEHYDROGENASE IN DROSOPHILA MELANOGASTER

Genetics ◽  
1978 ◽  
Vol 89 (2) ◽  
pp. 371-388
Author(s):  
John F McDonald ◽  
Francisco J Ayala
Keyword(s):  
Gene Regulation ◽  
Drosophila Melanogaster ◽  
Alcohol Dehydrogenase ◽  
Natural Populations ◽  
Difficult Problem ◽  
Regulatory Genes ◽  
Biochemical Basis ◽  
Evolutionary Consequence ◽  
The Third ◽  
Adh Activity

ABSTRACT Recent studies by various authors suggest that variation in gene regulation may be common in nature, and might be of great evolutionary consequence; but the ascertainment of variation in gene regulation has proven to be a difficult problem. In this study, we explore this problem by measuring alcohol dehydrogenase (ADH) activity in Drosophila melanogaster strains homozygous for various combinations of given second and third chromosomes sampled from a natural population. The structural locus (Adh) coding for ADH is on the second chromosome. The results show that: (1) there are genes, other than Adh, that affect the levels of ADH activity; (2) at least some of these "regulatory" genes are located on the third chromosome, and thus are not adjacent to the Adh locus; (3) variation exists in natural populations for such regulatory genes; (4) the effect of these regulatory genes varies as they interact with different second chromosomes; (5) third chromosomes with high-activity genes are either partially or completely dominant over chromosomes with low-activity genes; (6) the effects of the regulatory genes are pervasive throughout development; and (7) the third chromosome genes regulate the levels of ADH activity by affecting the number of ADH molecules in the flies. The results are consistent with the view that the evolution of regulatory genes may play an important role in adaptation.

NUMERICAL ANALYSIS OF RANDOM DRIFT IN A CLINE

Genetics ◽  
1980 ◽  
Vol 94 (2) ◽  
pp. 497-517
Author(s):  
Thomas Nagylaki ◽  
Bradley Lucier
Keyword(s):  
Natural Populations ◽  
The Other ◽  
Random Genetic Drift ◽  
Gene Frequencies ◽  
Random Drift ◽  
Linear Habitat ◽  
Asymptotic Formulae ◽  
A Chain ◽  
Average Position ◽  
Uniform Population

ABSTRACT The equilibrium state of a diffusion model for random genetic drift in a cline is analyzed numerically. The monoecious organism occupies an unbounded linear habitat with constant, uniform population density. Migration is homogeneouq symmetric and independent of genotype. A single diallelic locus with a step environment is investigated in the absence of dominance and mutation. The flattening of the expected cline due to random drift is very slight in natural populations. The ratio of the variance of either gene frequency to the product of the expected gene frequencies decreases monotonically to a nonzero constant. The correlation between the gene frequencies at two points decreases monotonically to zero as the separation is increased with the average position fixed; the decrease is asymptotically exponential. The correlation decreases monotonically to a positive constant depending on the separation as the average position increasingly deviates from the center of the cline with the separation fixed. The correlation also decreases monotonically to zero if one of the points is fixed and the other is moved outward in the habitat, the ultimate decrease again being exponential. Some asymptotic formulae are derived analytically.—The loss of an allele favored in an environmental pocket is investigated by simulating a chain of demes exchanging migrants, the other assumptions being the same as above. For most natural populations, provided the allele would be maintained in the population deterministically, this process is too slow to have evolutionary importance.

scholarly journals MOLECULAR POPULATION GENETICS OF THE ALCOHOL DEHYDROGENASE GENE REGION OF DROSOPHILA MELANOGASTER

Genetics ◽  
1986 ◽  
Vol 114 (4) ◽  
pp. 1165-1190
Author(s):  
Charles F Aquadro ◽  
Susan F Desse ◽  
Molly M Bland ◽  
Charles H Langley ◽  
Cathy C Laurie-Ahlberg
Keyword(s):  
Drosophila Melanogaster ◽  
Alcohol Dehydrogenase ◽  
Sequence Variation ◽  
Natural Populations ◽  
Restriction Map ◽  
Length Variation ◽  
Eastern United States ◽  
Chromosome Inversion ◽  
Frequency Spectra ◽  
Adh Activity

ABSTRACT Variation in the DNA restriction map of a 13-kb region of chromosome ll including the alcohol dehydrogenase structural gene (Adh) was examined in Drosophila melanogaster from natural populations. Detailed analysis of 48 D. melanogaster lines representing four eastern United States populations revealed extensive DNA sequence variation due to base substitutions, insertions and deletions. Cloning of this region from several lines allowed characterization of length variation as due to unique sequence insertions or deletions [nine sizes; 21-200 base pairs (bp)] or transposable element insertions (several sizes, 340 bp to 10.2 kb, representing four different elements). Despite this extensive variation in sequences flanking the Adh gene, only one length polymorphism is clearly associated with altered Adh expression (a copia element approximately 250 bp 5′ to the distal transcript start site). Nonetheless, the frequency spectra of transposable elements within and between Drosophila species suggests they are slightly deleterious. Strong nonrandom associations are observed among Adh region sequence variants, ADH allozyme (Fast vs. Slow), ADH enzyme activity and the chromosome inversion ln(2L)t. Phylogenetic analysis of restriction map haplotypes suggest that the major twofold component of ADH activity variation (high vs. low, typical of Fast and Slow allozymes, respectively) is due to sequence variation tightly linked to and possibly distinct from that underlying the allozyme difference. The patterns of nucleotide and haplotype variation for Fast and Slow allozyme lines are consistent with the recent increase in frequency and spread of the Fast haplotype associated with high ADH activity. These data emphasize the important role of evolutionary history and strong nonrandom associations among tightly linked sequence variation as determinants of the patterns of variation observed in natural populations.

scholarly journals Adaptedness of Variants at an Alcohol Dehydrogenase Locus in Bromus mollis L. (Soft Bromegrass)

1976 ◽  
Vol 29 (4) ◽  
pp. 389 ◽  
Author(s):  
ADH Brown ◽  
DR Marshall ◽  
J Munday
Keyword(s):  
Alcohol Dehydrogenase ◽  
Dehydrogenase Activity ◽  
Dry Matter ◽  
Animal Species ◽  
Natural Populations ◽  
Continuous Flooding ◽  
Naturally Occurring ◽  
Alcohol Dehydrogenase Activity ◽  
Adh Activity ◽  
Bromus Mollis

Alcohol dehydrogenase is highly polymorphic in many plant and animal species. Here we report evidence that the naturally occurring, electrophoretically detectable allozyme variants of the AdhlB locus in B. mollis can respond differentially to environmental stresses. It is argued that alcohol dehydrogenase activity is specifically involved in response to these stresses. Crude extracts of predominantly selfed seeds sampled from plants of known Adh1B genotype were assayed for their ADH activity in the forward and backward reactions. The seeds from Adh~B Adh~B plants produced extracts about 12 % less active in both directions than seeds from their Adh~BAdh~B counterparts. Such Adh~BAdh~B plants were also shown to produce about 13% more dry matter when grown under continuous flooding in the greenhouse whereas no difference between genotypes was detected in control pots. The seeds of Adh~B Adh~B plants showed an advantage over the alternative homozygotes in more rapid germination at 2�C, but no difference was found at 15�C. Thus the variants are differentially adapted, and this is likely to playa role in the maintenance of the polymorphism in natural populations.

Statistics of Natural Populations. III. Sequential Sampling Plans for the Estimation of Gene Frequencies

Biometrics ◽  
1986 ◽  
Vol 42 (1) ◽  
pp. 45 ◽  
Author(s):  
Marc J. Sobel ◽  
Jonathan Arnold ◽  
Milton Sobel
Keyword(s):  
Sequential Sampling ◽  
Natural Populations ◽  
Gene Frequencies ◽  
Sampling Plans

scholarly journals Enzyme variability in the Drosophila willistoni Group. V. Genic variation in natural populations of Drosophila equinoxialis

1972 ◽  
Vol 20 (1) ◽  
pp. 19-42 ◽  
Author(s):  
Francisco J. Ayala ◽  
Jeffrey R. Powell ◽  
Martin L. Tracey
Keyword(s):  
Genetic Variation ◽  
Allelic Variation ◽  
Natural Populations ◽  
Starch Gel Electrophoresis ◽  
Gene Frequencies ◽  
Group V ◽  
Neutral Genetic Variation ◽  
Starch Gel ◽  
Genic Variation ◽  
Standard Techniques

SUMMARYWe have studied genetic variation at 27 loci in 42 samples from natural populations of a neotropical species, Drosophila equinoxialis, using standard techniques of starch-gel electrophoresis to detect allelic variation in genes coding for enzymes. There is considerarle genetic variability in D. equinoxialis. We have found allelic variation in each of the 27 loci, although not in every population. On the average, 71% of the loci are polymorphic – that is, the most common allele has a frequency no greater than 0·95 – in a given population. An individual is heterozygous on the average at 21·8% of its loci.The amount of genetic variation fluctuates widely from locus to locus. At the Mdh-2 locus arout 1% of the individuals are heterozygotes; at the other extreme more than 56% of the individuals are heterozygous at the Est-3. At any given locus the configuration of allelic frequencies is strikingly similar from locality to locality. At each and every locus the same allele is generally the most common throughout the distribution of the species. Yet differences in gene frequencies occur between localities. The pattern of genetic variation is incompatible with the hypothesis that the variation is adaptively neutral. Genetic variation in D. equinoxialis is maintained by balancing natural selection.The amount and pattern of genetic variation is similar in D. equinoxialis and its sibling species, D. willistoni. Yet the two species are genetically very different. Different sets of alleles occur at nearly 40% of the loci.

scholarly journals A theoretical analysis of linkage disequilibrium produced by genetic drift in Drosophila populations

1986 ◽  
Vol 48 (3) ◽  
pp. 161-166 ◽  
Author(s):  
Catherine Montchamp-Moreau ◽  
Mariano Katz
Keyword(s):  
Linkage Disequilibrium ◽  
Genetic Drift ◽  
Statistical Tests ◽  
Burst Size ◽  
Natural Populations ◽  
Finite Size ◽  
Gene Frequencies ◽  
Accurate Knowledge ◽  
Maximum Value ◽  
Cyclical Fluctuations

SummaryWe analyse the progression of linkage disequilibrium produced by random genetic drift in populations subject to cyclical fluctuations in size. Our model is applied to natural populations of Drosophila which show an annual demographic cycle of bottleneck (finite size) and demographic burst (size supposed to be infinite). In these populations, linkage disequilibrium stabilizes in such a way that, at equilibrium, the expected square of the correlation of gene frequencies E(r2) shows a stable cycle from year to year. If two loci are tightly linked, E(r2) barely varies during the annual cycle. Its values remain close to the value expected in a population of the same but constant effective size. If two loci are loosely linked, fluctuations in E(r2) are large. The maximum value, reached at the end of the bottleneck, is 10 to 100 times greater than the value obtained at the end of the burst. Our results show that the interpretation of observed linkage disequilibrium, by means of statistical tests, requires an accurate knowledge of population demography.

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