Natural Populations Of Drosophila Research Articles

Extensive variation and heteroplasmy in size of mitochondrial DNA among geographic populations of Drosophila melanogaster

Size variation and heteroplasmy in mitochondrial DNA (mtDNA) are relatively common in natural populations of Drosophila melanogaster. Of 92 isofemale lines of flies obtained from various geographic regions throughout the world, 75 lines were homoplasmic and showed a total of 12 different mtDNA size classes. The remaining 17 lines were heteroplasmic, each line carrying two different mtDNAs, and, in all but one case, the mtDNAs in these heteroplasmic lines differed in size; a total of nine size classes was represented among them. In cases where one type was predominant within an individual, it was usually the smaller mtDNA. This finding parallels what was observed in homoplasmic lines, in that the smaller mtDNAs were much more common than the larger variants in most populations. The data suggest a high rate of mutational occurrence of mtDNA size variants and some natural selection against them.

Perpetuation of the hereditary sigma virus in populations of its host, Drosophila melanogaster. Geographical analysis of correlated polymorphisms

In natural populations of Drosophila melanogaster, about 10% of the individuals are infected by a virus, sigma, which is not contagious but is transmitted through gametes. These populations are also regularly polymorphic for two alleles, O and P, of a locus ref(2)P; the P allele interferes with the multiplication of the virus. Two viral Types are found in populations, differing in their sensitivity to the P allele. Many samples of flies have been collected in different parts of the world and for each of them, the P frequency has been measured and the viral Type determined. A clear geographical differentiation appears for both these traits; they present a mutual adaptation leading to relatively low frequencies of infected flies in natural populations. Most viruses are only known from highly selected laboratory strains. The observations reported in this paper give evidence of the self restraint exercised by the sigma virus at the population level; they indicate that the characteristics of wild viral clones are likely to differ from those of laboratory strains and also from one population to another.

Genetic analysis of Drosophila melanogaster in the French West Indies and comparison with populations from other parts of the world

Four natural populations of Drosophila melanogaster, three from Guadeloupe and one from Martinique (French West Indies), were studied with respect to four types of genetically determined traits, namely allozyme frequencies, morphology, ethanol tolerance, and oviposition rhythm. These populations were compared to European (France) and tropical African populations, and, with respect to allozymes alone, to an American population. The four populations from the West Indies were found to be genetically similar; this may reflect a common historical origin, or an adaptive response to similar environmental pressures or possibly some gene flow between the two islands. The comparisons with distant populations led to different conclusions depending upon the trait considered. In the case of allozymes, flies from the West Indies were more similar to tropical African populations than to an American population from Texas, but the main difference observed was in comparison with European populations. The morphology of the West Indies flies resembled a smaller, tropical type, but the size was even smaller than observed in Africa. Both ethanol tolerance and oviposition rhythm were intermediate between flies from tropical Africa and Europe. All these results can be explained in terms of interactions between selection imposed by a tropical environment and the genetic properties of the founder population which first colonized the islands.

Analysis of Aldoxn alleles isolated from natural populations of Drosophila melanogaster.

Aldox "null" alleles which were isolated from natural populations in Great Britain and North Carolina were analyzed for complementation. No complementation was observed between any combinations of "null" alleles for aldehyde oxidase (AO) specific activity in late third-instar larvae and newly emerged adults. AO immunologically cross-reacting material (AO-CRM) was quantitated in all homozygous stocks at both developmental stages as well as all allelic combinations in newly emerged adults. When the adult organism contains only Aldoxn alleles, the polypeptides are not immunologically recognizable or may be rapidly degraded. Larvae and adults have different abilities to degrade mutationally altered enzymatically inactive AO polypeptide or synthesize them differentially. This is indicated by easily measurable AO-CRM levels in late third-instar larvae of Aldoxn homozygotes, while newly emerged adult Aldoxn homozygotes have very little, if any, AO-CRM. Newly emerged adult heterozygotes of Aldoxn/Aldox+ do have increased AO-CRM, indicating that the Aldoxn alleles can code for a polypeptide which can be "rescued" if Aldox+ gene product is present. Heterozygotes containing an Aldox+ allele with a deficiency for the Aldox region produce 74.2% of the AO-CRM found in Aldox+ homozygotes. This may indicate the presence of trans-acting factors which serve to activate gene expression in a system in which each gene copy is not maximally expressed.

Dominance for sn-glycerol-3-phosphate dehydrogenase activity in Drosophila melanogaster: Evidence for differential allelic expression mediated via a trans-acting effect

Two second chromosomes (H31 and T198) which when homozygous give relatively low α glycerol-3-phosphate dehydrogenase (GPDH) activity have been isolated from natural populations of Drosophila melanogaster. In heterozygotes between H31 and T198 and chromosomes bearing standard Gpdh alleles there is dominance for GPDH activity and for the amount of GPDH protein. The increased level of activity in the heterozygotes appears to be due to the differential expression of the standard alleles rather than to increased heterodimer activity. Recombination analyses have shown that if the effect is due to a modifier it must be less than 0·04 cM from the Gpdh locus.

Persistence of an alcohol dehydrogenase thermostable variant in a natural population of Drosophila melanogaster.

SUMMARYA temporal survey of the alcohol dehydrogenase locus in a natural population ofDrosophila melanogasterfrom the Canary Islands has revealed the existence of an electrophoretic Fast thermostable variant, mapped within 0.8 units of the structuralAdhlocus, and which persists over a 6-year period with a frequency ranging from 0.8 to 0.5%.

Genetic complexity of host-selection behavior in Drosophila

Genetic variation for settling responses to different types of food and for oviposition behavior exists within natural populations of Drosophila tripunctata. After flies from two isofemale strains and F(2) derived from crosses between them were released in the wild and recaptured at either mushroom or tomato baits, the oviposition preferences of females for these foods were determined in the laboratory. Whereas settling behavior and oviposition-site preference were negatively correlated in the parental strains, there was no association of these behaviors in the F(2) generation. Furthermore, lines produced by crossing these two strains followed by inbreeding did not manifest such a negative correlation. Together, these results indicate that two important aspects of host selection are under independent genetic control. These findings caution against using a single component of the process of host selection as indicative of the probability that a particular resource will be utilized in the field, and they bear on the question of how speciation based on genetic variation for host selection may be accomplished.

Mitochondrial DNA variability in natural populations of Hawaiian Drosophila. I. Methods and levels of variability in D. silvestris and D. heteroneura populations

We describe techniques by which mitochondrial DNA (mtDNA) restriction site information can be obtained for up to 16 different restriction endonucleases on individual Hawaiian Drosophila, in particular D. silvestris and D. heteroneura. We have constructed mtDNA restriction site maps for a total of forty-eight wild caught genomes of both species, from seven major collecting sites on the island of Hawaii. Levels of variability are, in general, high in D. silvestris (p of Ewens et al., 1981 = 0.0486) and lower in D. heteroneura (p = 0.0327). Measures of population subdivision using Nei's Gst indicate that about 50-60 per cent of the observed variability is due to interdemic subdivision. In accordance, populations within a species show a much lower level of variability, however some populations harbour individuals that are very divergent from the rest of their conspecifics at the same locality. We review two possible mechanisms that could explain the presence of these divergent individuals, hybridisation and the effects of stochastic branching processes.

A quantitative genetic analysis of fitness and its components inDrosophila melanogaster

SummaryForty-one third chromosomes extracted from a natural population ofDrosophila melanogasterwere assessed for net fitness and for the quantitative characters viability, net fertility, female productivity, male weight, abdominal bristle number, and sternopleural bristle number. Net homozygous and heterozygous fitness of the third chromosomes was estimated by competition against a marked balancer third chromosome. Average fitness of the homozygous lines relative to wild-type heterozygotes was 0·13, indicating substantial inbreeding depression for net fitness. All significant correlations of quantitative characters with fitness and with each other were high and positive. Homozygous fitness is strongly correlated with net fertility, viability, and female productivity, moderately associated with male weight, and not significantly associated with bristle traits. The combination of metric traits which best predicts homozygous fitness is the simple multiple of viability and female productivity. Heterozygous fitness is not correlated with homozygous fitness; furthermore, the relative contribution of metric traits to fitness in a heterozygous population is likely to be different from that deduced from homozygous lines. These observations are consistent with a model of genetic variation for fitness in natural populations caused by segregation of rare deleterious recessive alleles.

Genetic analysis of natural populations of Drosophila melanogaster in Japan. V Genetic variabilities of amylase activities in different developmental stages and theil relation to fitness.

Genetic variation of regulatory genes with respect to the amylase activities in different developmental stages (developmental inducibility) as well as the inducibility (S/N) which was studied in the previous reports (Yamazaki and Matsuo 1984), was found among 10 isogenic strains established from a natural population of Drosophila melanogaster. Net fitness of each of these 10 strains was obtained from interspecific competition experiments and the correlation between fitness and inducibilities of amylase was calculated; No correlation was obtained between developmental inducibility and fitness. On the other hand, a significant positive correlation was obtained between fitness and inducibility (S/N) (γp=0.48* and γg=0.95). This indicates that these two types of regulatory gene polymorphisms are different in nature, and that regulatory patterns of the enzymes which are found in different developmental stages under normal environments have little to do with adaptability of flies.

Genetic analysis of natural populations of Drosophila melanogaster in Japan. VI Differential regulation of duplicated amylase loci and degree of dominance of amylase activity in different environments.

The degrees of dominance of amylase activity, responsiveness to inducing (or repressive) environment, the activity of one allozyme relative to that of the other duplicated locus, and trans- or cis-action of controlling elements were investigated using 10 homozygous lines from a natural population in Japan. The main findings are: (1) Genetic variation in specific activity, responsiveness as well as relative activity of duplicated genes were found. (2) The degree of dominance of amylase activity drastically changed in different environments. The heterozygous amylase activity in starch food was almost the same as the parental value with lower activity (h=1.29±0.39, complete recessive). On the other hand, the enzyme activity of heterozygote in normal food was closer to the parent with higher activity (h=0.26 ±0.07, high dominance), indicating that the manner of amylase regulation is trans-action and also is affected by the environments. (3) The relative activity of one of the two duplicated amylase loci on the same chromosome was affected by an allozyme on the homologous chromosome. In other words, the regulation of duplicated amylase genes was trans-action and partially differentiated, but high correlation of the enzyme activity between the two duplicated genes on the same chromosome also indicated the coordinated regulation.

Alcohol dehydrogenase and sn-glycerol-3-phosphate dehydrogenase null activity alleles in natural populations of Drosophila melanogaster

Alcohol dehydrogenase (Adh) null activity alleles have been detected in each of 2 years in Australian populations of D. melanogaster at frequencies up to 3·9 per cent, but with an average of 1·3 per cent in 1983 and 0·7 per cent in 1984. In the same populations the frequency of sn-glycerol-3-phosphate dehydrogenase (Gpdh) null alleles was as high as 2·7 per cent with an average of 1·6 per cent in 1983 and 0·5 per cent in 1984. These values compare with previously reported frequencies of 0·09 per cent for Adh and 0·8 per cent for Gpdh in a North Carolina (U.S.A.) and a London (U.K.) population. Of the 12 second chromosomes bearing Adh null alleles, four were homozygous lethal, but all were viable and fertile in combination with Df(2L)64j.

Detection of simple polygenic segregations in a natural population

Penetrance frequencies were used to quantify segregating polygenic effects in a natural population of Drosophila melanogaster. When males from a series of 100 isofemale strains were crossed to females from a veinlet (ve) line that had been selected for shortened veins, gaps commonly appeared in the fifth longitudinal (L5) vein in the ve/+ heterozygotes. We were able to assign each strain to one of six significantly different clusters, based upon the pattern of polygenic modifiers of ve dominance segregating in each strain. We conclude that the extensive range of phenotypic variation in vein-forming ability is actually based upon a relatively simple underlying polygenic structure that is consistent with segregation of only a small number of alleles or allele combinations in the wild population.

THE GENETIC STRUCTURE OF NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER. XIX. GENOTYPE-ENVIRONMENT INTERACTION IN VIABILITY

To investigate whether or not an excess of additive genetic variance for viability detected in southern natural populations of Drosophila melanogaster was created by diversifying selection, genotype-environment interaction was tested as follows. (1) Two karyotype chromosomes were used: 61 second chromosomes with the standard karyotype and 63 second chromosomes carrying In(2L)t. Their homozygote viabilities were larger than 50% of the average viability of random heterozygotes. (2) The effects of two factors (culture media and yeasts) were examined at three levels (the culture media: tomato, corn and banana; and the yeasts: sake, brewer's and baker's). The results of 16 three by three factorial experiments by the Cy method in the same karyotype groups for relative viabilities of homozygotes and heterozygotes elucidated the following findings: (1) there was no significant difference between the two karyotype groups, (2) the variance components of genotype-environment interaction were highly significant, (3) the variance component of heterozygotes was significantly smaller than that of homozygotes. From the experimental findings and previous results, diversifying selection in natural populations acting on viability polygenes to increase the additive genetic variance was suggested. The relation of the present result to protein polymorphism is also discussed.

Annual variation of enzyme polymorphism in four natural populations ofDrosophila melanogaster occupying different niches

Gene and gametic frequencies of theAdh, Aox, α-Gpdh andEst-6 loci (map position: II-50.I, III-56.6, II-20.5 and III-36.0 respectively) have been studied in two wine cellar populations at 40 km distance from each other, and two field populations, one near each of the wine cellars. Only one locus,Aox was polymorphic for more than two electromorphs. TheAdh locus seems to follow a different mode of change in genic frequencies in wine cellars, than in the field, while the other loci exhibit a similar pattern of polymorphism in the field and in the wine cellar. Linkage disequilibrium in the gameteAdh/α-Gpdh is affected by different phenomena in the field than in the wine cellar. A stronger linkage disequilibrium in theAdh/gametes observed in the field, may be a consequence of a mixture of subpopulations subjected to differential selection at theAdh locus. TheAdh locus is the only one in which selection is detected in one environment. It is neutral in other environments. Theα-Gpdh, Aox andEst-6 polymorphisms, however, behave as though they were neutral both in the wine cellar and in the field.

Variation in alcohol dehydrogenase activity in vitro in flies from natural populations ofDrosophila melanogaster

Alcohol dehydrogenase (ADH) activity variation in male flies taken directly from seven natural populations ofDrosophila melanogaster is largely accounted for by segregation of alleles at theAdh structural gene locus. There was little overlap in the ADH activities ofAdhF andAdhs homozygotes. Body weights varied only slightly betweenAdh genotypes and contributed little to ADH variation. Between and within population variation in ADH activity and ADH protein in flies in the wild is mainly due to the relative frequencies ofAdhF andAdhs.

Electrophoretic and heat-stability polymorphism at the phosphoglucomutase (Pgm) locus in natural populations of Drosophila melanogaster.

Genetic polymorphism for electrophoretic and heart-sensitive alleles is known at the phosphoglucomutase (Pgm) locus in Drosophila melanogaster. Analysis of the distribution of electrophoretic and thermosensitive (ts) alleles was carried out in natural populations from Canada and West Africa and compared with already known data on Italian populations [Trippa, G., Loverre, A., and Catamo, A. (1976). Nature 260:42]. The data show the existence of five common alleles, Pgm1.00,tr, Pmg1.00,ts, Pgm0.70,ts, Pgm1.20,ts, and Pgm1.50,tr, and two rare alleles, Pgm0.55,ts and Pgm1.20,tr. The most frequent allele is always Pgm1.00,tr; the second most common allele is always of the ts type. The cumulated frequencies of ts alleles in the populations varies between 11 and 32%. The heat stability polymorphism is present in all populations examined and shows again the uniform geographic pattern that has been found for electrophoretic variation at this locus.

Allozyme variation in fourteen natural populations of Drosophila melanogaster collected from different regions of France

Allozyme variation in fourteen natural populations of Drosophila melanogaster collected from different regions of France

Superoxide dismutase in Drosophila melanogaster: Mutation site difference between two electromorphs

Two electrophoretically distinguishable variants of Superoxide dismutase (SOD) are common in natural populations of Drosophila melanogaster. We have earlier comparatively characterized these two electromorphs, SOD F and SOD S By peptide mapping in high-performance liquid chromatography (HPLC), we now show that the difference between the two electromorphs is due to the replacement of Asn-96 (SOD F) by Lys-96 (SOD s). It is far from clear how this replacement causes the biochemical differences (in thermostability, specific activity, and others) observed between these two forms of the enzyme.

Allozyme variation in fourteen natural populations of Drosophila melanogaster collected from different regions of France

Allozyme variation in fourteen natural populations of Drosophila melanogaster collected from different regions of France