Drosophila Immigrans Research Articles

English

  Post monsoon studies were conducted to analyze the altitudinal variation in a population ofDrosophila (Diptera: Drosophilidae) in Brahmagiri Wildlife Sanctuary belonging to the Western Ghats of Coorg district, Karnataka State, India. A total of 4636 Drosophila flies belonging to 8 species of 3 subgenera were collected at altitudes of 800, 900 and 1000 m. The subgenusSophophora was predominant with 5 different species, subgenus Drosophila with 2 different species and the subgenus Scaptodrosophila was least represented with only a single species. The population density varied in the above three altitudes and highest density was found at 800 m, then the density reduced at 900 m (380 flies) and once again the density increased at 1000 m. This shows that Drosophila community is affected by elevation. The diversity of theDrosophila community was also assessed by applying the Simpson and Berger-Parker indices. At 800 m, the Simpson Index was low at 0.37 and the Berger-Parker index was high at 0.47, 900 m. The distributional pattern of a species or related group of species was uneven in space and time. Drosophila kikkawai, Drosophila takahashii, Drosophila immigrans and Drosophila nigrawere found in all the three altitudes suggesting that these species are dominant in this region.   Key words: Drosophila, Brahmagiri Wildlife Sanctuary, Drosophila kikkawai, Drosophila takahashii, Drosophila immigrans, Drosophila nigra.

Divergence for tolerance to thermal-stress related traits in two Drosophila species of immigrans group

We investigated associations of the species specific divergence of thermal adaptations of Drosophila nasuta and Drosophila immigrans with seasonal as well as geographical changes in the relative abundance. In D. immigrans, cold resistance and egg-to-adult viability after a cold-shock have shown a positive cline with latitude, whereas no such clinal patterns were evident for heat resistance as well as egg-to-adult viability after heat stress. In contrast, basal heat tolerance and egg-to-adult viability after a heat-shock increased towards the equator i.e. from north to south in D. nasuta. Further, we also found species-specific divergence in seasonal climatic selection responses for heat as well as cold resistance i.e. warmer and higher humidity conditions of the rainy season have evidenced ∼2-fold higher heat tolerance of D. nasuta, but lower temperature as well as lower humidity conditions of the autumn significantly increased (∼3-fold) cold tolerance of D. immigrans. Geographical variations were significant for the absolute and relative hardening capacity for cold tolerance in D. immigrans, but for heat resistance of D. nasuta. Results of multiple regression analysis of changes in thermal tolerance level in latitudinal populations as a simultaneous function of climatic variables (Tave and RH) have shown that average yearly relative humidity levels significantly affect heat tolerance of D. nasuta, but both Tave and RH contribute to changes in the cold tolerance of D. immigrans. Thus, our results suggest that climatic selection responses for basal and hardened thermo-tolerance levels affect relative abundance of D. nasuta and D. immigrans across a latitudinal transect as well as seasons.

Evidence for no sexual isolation between Drosophila albomicans and D. nasuta

Sexual isolation, the reduced tendency to mate, is one of the reproductive barriers that prevent gene flow between different species. Various species-specific signals during courtship contribute to sexual isolation between species. Drosophila albomicans and D. nasuta are closely related species of the nasuta subgroup within the Drosophila immigrans group and are distributed in allopatry. We analyzed mating behavior and courtship as well as cuticular hydrocarbon profiles within and between species. Here, we report that these two species randomly mated with each other. We did not observe any sexual isolation between species or between strains within species by multiple-choice tests. Significant difference in the courtship index was detected between these two species, but males and females of both species showed no discrimination against heterospecific partners. Significant quantitative variations in cuticular hydrocarbons between these two species were also found, but the cuticular hydrocarbons appear to play a negligible role in both courtship and sexual isolation between these two species. In contrast to the evident postzygotic isolation, the lack of sexual isolation between these two species suggests that the evolution of premating isolation may lag behind that of the intergenomic incompatibility, which might be driven by intragenomic conflicts.

Diversity and abundance of frugivorous drosophilids and their parasitoids in Bogor, Indonesia

The diversity, abundance and association of frugivorous drosophilids and their parasitoids were studied in Bogor, Indonesia (tropical region), and compared with the results in Iriomote-jima (subtropical region) and Tokyo (temperate region). Among the adult drosophilid flies collected in traps baited with banana in wooded areas, the number of commonly observed frugivorous drosophilid species (i.e. species that occupied more than 0.5% of total drosophilid samples) was 10 in Bogor and nine in Iriomote-jima, more than in Tokyo (six species), probably reflecting the high diversity and abundance of fruits. The rate of parasitism was very high in Bogor, especially in species of the Drosophila ananassae and immigrans species groups. The diversity of parasitoids attacking frugivorous drosophilids was higher in Bogor and Iriomote-jima than in Tokyo, possibly because of the high species diversity of host drosophilids. Parasitoids generally showed wider latitudinal distributions than drosophilids. No remarkable difference was observed in the host range among tropical, subtropical and temperate parasitoids.

Polyphyly of the Zaprionus genus group (Diptera: Drosophilidae)

The Zaprionus genus group comprises three drosophilid genera (Zaprionus, Phorticella and Samoaia) that are thought to be related to the Drosophila immigrans species group. We revised the phylogenetic relationships among the three genera and their placement within the subfamily Drosophilinae using one mitochondrial (COII) and one nuclear (Amyrel) gene. The Bayesian tree inferred from concatenated amino acid sequences of the two genes strongly suggests the polyphyly of the Zaprionus genus group and of each of the genera Zaprionus and Phorticella. Paraphyly of the D.immigrans species group was also shown here; the quadrilineata subgroup formed the sister clade to the genus Samoaia. These results suggest the necessity of taxonomic revisions for some relevant genera and species groups included within the genus Drosophila.

Taxonomic review of the Australian Drosophila setifemur species group, a new name for the D. dispar species group (Diptera: Drosophilidae)

Examination of the holotype and a paratype of Drosophila setifemur Malloch, 1924 in the Australian Museum has resulted in the discovery that it is not a synonym of D. sulfurigaster as had previously been assumed. Instead, D. setifemur is a senior synonym of the widespread eastern Australian species D. dispar Mather, 1955. The so-called Drosophila dispar species group is renamed the Drosophila setifemur species group and Drosophila unguicula is removed from it. An illustrated key to Australian drosophilids with spinescent fore-femora is provided. Mcevey, Shane F., 2009. Taxonomic review of the Australian Drosophila setifemur species group, a new name for the D. dispar species group (Diptera: Drosophilidae). Records of the Australian Museum 61(1): 31–38. The genus Drosophila accommodates a great range of drosophilids, with numerous aggregations at various levels between genus and species (viz. subgenus, species group, subgroup, complex, etc.). A rapidly growing body of knowledge is allowing us to know with ever increasing certainty the true genetic relationship between species. But ultimately, even when the tree that relates every lab strain and every field-sampled specimen is known with a high level of confidence, there will remain the task of affixing the taxonomically valid names to each of those samples and to biological species. Drosophila currently has c. 1,600 described species; c. 350 are classified with D. melanogaster in the subgenus Sophophora, and another c. 730 species are treated as Drosophila s.str. Nearly all are attracted to fruit baits and can be established as cultures in the laboratory. The following synonymy involves Drosophila dispar Mather, 1955: 570 (a species in the dispar species group of the Drosophila subgenus Sophophora) and D. setifemur Malloch, 1924: 351 (a species incorrectly classified as synonymous with D. sulfurigaster (Duda, 1923: 48) in the nasuta subgroup, immigrans species group of Drosophila s.str.). Removing D. setifemur from synonymy with D. sulfuri­ gaster and placing it in synonymy with D. dispar leads to a need to rename the Drosophila dispar species group (established by Mather,1955).

Body size and mating success in drosophila immigrans: A field study

Body size and mating success in drosophila immigrans: A field study

The effect of travel time on oviposition behavior and spatial egg aggregation: experiments with Drosophila

AbstractA higher degree of spatial egg aggregation is often observed in environments where resource patches are more sparsely distributed. This suggests a higher probability of species coexistence when resource distribution is sparse. However, it is still unclear how the degree of spatial egg aggregation increases. I propose a model to explain this phenomenon, which assumes that (i) egg load (the number of mature eggs in ovaries) increases in the travel period between resource patches and (ii) the retention of eggs in the ovaries is harmful (egg load pressure). With these assumptions, a female would lay accumulated eggs on arrival at a new resource patch, resulting in a higher degree of spatial egg aggregation. Laboratory experiments with three drosophilid species, Drosophila simulans Surtevant, Drosophila auraria Peng, and Drosophila immigrans Sturtevant, support the model. This study provides evidence that host availability affects the spatial egg aggregation via egg load.

Tolerance of Drosophila Flies to Ibotenic Acid Poisons in Mushrooms

The mushroom genus Amanita has a spectrum of chemical compounds affecting survival and performance of animals. Ibotenic acid is one of such compounds found in some Amanita mushrooms. We studied the effects of ibotenic acid and its derivative, muscimol, on egg-to-pupa survival, pupation time, and pupal size in five Drosophila species (Diptera: Drosophilidae), Drosophila bizonata, Drosophila angularis, Drosophila brachynephros, Drosophila immigrans, and Drosophila melanogaster. The first three species are mycophagous and use a wide range of mushrooms for breeding, whereas D. immigrans and D. melanogaster are frugivorous. We reared fly larvae on artificial medium with 500, 250, 125, and 62.5 microg/ml of ibotenic acid and/or musimol. The three mycophagous species were not susceptible to ibotenic acid, whereas the two frugivorous species were affected. In experiments with D. melanogaster, muscimol was less toxic than ibotenic acid.

Molecular phylogeny of the <i>nasuta</i> subgroup of <i>Drosophila </i>based on 12S rRNA, 16S rRNA and CoI mitochondrial genes, RAPD and ISSR polymorphisms

The nasuta subgroup is a cluster of morphologically almost similar forms with a wide range of geographic distribution. During the last three decades nature of inter-relationship among the members has been investigated at different levels of organization. The phylogenetic relationships of the members of the nasuta subgroup of the immigrans species group of Drosophila was made by employing Random Amplified Polymorphic DNA (RAPD), Inter Simple Sequence Repeats-PCR (ISSR-PCR) polymorphisms, mitochondrial 12S rRNA, 16S rRNA and Cytochrome C Oxidase subunit I (CoI) gene sequences. The phylogenetic tree generated by RAPD analysis is in nearly complete congruence with the classification based on morphophenotypic characters. The 12S and 16S rRNA genes were highly conserved across the nasuta subgroup and revealed only 3 and 4 variable sites respectively, of which only one site was informative. The CoI gene, on the other hand, revealed 57 variable sites of which 25 sites were informative. All the three species of orbital sheen complex were included in a major cluster in the phylogenetic trees derived from mitochondrial gene sequence data consistent with the morphophenotypic classification. The CoI analysis placed two species of frontal sheen complex, D. n. nasuta and D. n. albomicans in two different clades and this is inconsistent with morphological classification. The molecular clock suggested that divergence between the kohkoa complex and the albomicans complex occurred approximately 2.2 MYA, indicating recent evolution of the nasuta subgroup. The higher transition bias in the mitochondrial genes reported in the present study also suggested recent evolution of the nasuta subgroup.

Chromosomal Polymorphism in Korean Natural Populations of Drosophila immigrans

ABSTRACT To analyze chromosome inversions of Drosophila immigrans, wild flies were captured from large vineyards located in the suburbs of Yecheon and Gyeongsan from October 1999 to 2001. With the egg samples obtained singly at each of the 799 females of D. immigrans, cytological examinations were carried out for the type and frequency of inversions. Two types of different inversions were found only in the second chromosome. The inversions detected were known to be the cosmopolitan inversion “A” and “B”. The mean frequency of inversion A was estimated to be 0.074 in Yecheon and 0.066 in Gyeongsan and that of B was to be 0.026 in Yecheon and 0.021 in Gyeongsan, respectively. In the frequency ratio, inversion A was significantly higher than that of B. The present populations of D. immigrans showed subtle differences from other Korean populations in inversion frequencies. To account for the local variations observed in inversion frequencies, several hypotheses are discussed such as founding event or selective force.

Evolutionary experimentation through hybridization under laboratory condition in Drosophila: Evidence for Recombinational Speciation

BackgroundDrosophila nasuta nasuta (2n = 8) and Drosophila nasuta albomicans (2n = 6) are a pair of sibling allopatric chromosomal cross-fertile races of the nasuta subgroup of immigrans species group of Drosophila. Interracial hybridization between these two races has given rise to new karyotypic strains called Cytorace 1 and Cytorace 2 (first phase). Further hybridization between Thailand strain of D. n. albomicans and D. n. nasuta of Coorg strain has resulted in the evolution of two more Cytoraces, namely Cytorace 3 and Cytorace 4 (second phase). The third phase Cytoraces (Cytorace 5 to Cytorace 16) have evolved through interracial hybridization among first, second phase Cytoraces along with parental races. Each of these Cytoraces is composed of recombined genomes of the parental races. Here, we have made an attempt to systematically assess the impact of hybridization on karyotypes, morphometric and life history traits in all 16 Cytoraces.ResultsThe results reveal that in most cases, the newly evolved Cytoraces, with different chromosome constitutions, exhibit decreased body size, better fitness and live longer than their parents. Particularly, Cytorace 5, 6 and 8 have evolved with very much higher range values of quantitative traits than the parents and other Cytoraces, which suggests the role of transgressive segregation in the evolution of these Cytoraces.ConclusionThus, the rapid divergence recorded in the chromosomes, karyotypes, body size and fitness traits of Cytoraces exhibit the early event of recombinational raciation / speciation in the evolution of the Cytoraces under laboratory conditions.

Coexistence of drosophilid flies: Aggregation, patch size diversity and parasitism

We carried out field experiments to investigate the coexistence of Drosophila species in domestic and forest areas on the basis of the aggregation model. Three cosmopolitan species Drosophila simulans Sturtevant, Drosophila melanogaster Meigen and Drosophila immigrans Sturtevant, and a native species, Drosophila auraria Peng, emerged abundantly from banana placed at the domestic station, while Drosophila immigrans and five native species, Drosophila lutescens Okada, Drosophila rufa Kikkawa and Peng, Drosophila bizonata Kikkawa and Peng, Drosophila sternopleuralis Okada and Kurokawa and Scaptodrosophila coracina (Kikkawa and Peng), were abundant at the forest station. The present analysis suggests that their coexistence was facilitated by the aggregation mechanism. In the cosmopolitan species, the density of individuals that emerged from patches increased with the increase of patch size, but the relationship between fly density and patch size was not clear in the native species. This difference in distribution patterns between the cosmopolitan and native species is likely to be due to the difference in the female visiting behavior. In the present analysis, however, it was not clear whether patch size diversity facilitated their coexistence or not. The effect of patch size diversity may have been masked, because the effect of aggregation was more prominent. The rate of parasitism by wasps was high in October at the domestic station, and in May and June at the forest station. The present result suggests that the rate of parasitism was density‐dependent, at least at the domestic station, and therefore parasitism facilitates the coexistence of drosophilid species in domestic areas.

Nontarget Insect Attraction to Methyl Eugenol Traps Used in Male Annihilation of the Oriental Fruit Fly (Diptera: Tephritidae) in Riparian Hawaiian Stream Habitat

This study set out to identify insect species associated with the riparian habitat of Hawaiian streams that were susceptible to deployment of the plant kairomone, methyl eugenol, used in male annihilation of the oriental fruit fly, Bactrocera dorsalis (Hendel). Sixteen nontarget insect species (13 Diptera and 3 Coleoptera) were found to be attracted to methyl eugenol traps deployed in riparian habitat in a variety of stream ecotypes at various elevations. Only 2 Diptera attracted to the lure, Drosophila perissopoda Hardy and D. Crucigera Grimshaw (Drosophilidae), were Hawaiian endemics, whereas the remainder were alien (nonnative) species. Alien drosophilids Drosophila immigrans Sturtevant and D. suzukii (Matsumura) and alien Desmometopa tarsalis Loew (Milichiidae) were the most abundant species captured in traps overall. Both plant-associated as well as carrion-associated species were captured in methyl eugenol traps. It is suggested that the fruiting cycle of wild guava, Psidium guajava and P. cattelianum , in mountainous and lowland areas of Hawaii is an important mechanism driving the population dynamics of insects attracted to methyl eugenol traps. Host plant demographics and species similarities in ecological requirements are important factors influencing the occurrences of susceptible species between sites. Seasonal periods of low oriental fruit fly numbers coupled with low abundances of nontarget insects create windows of opportunity during which male annihilation procedures with methyl eugenol can achieve maximum effect with minimal environmental risk. Environmentally acceptable use patterns for methyl eugenol can be developed through the modification of delivery systems and adaptation of these systems in surgical procedures tailored to specific ecotypes. These procedures can then provide Hawaiian agriculture with badly needed farm-level or area-wide control of destructive oriental fruit flies.

Regulation of Yolk Protein 2 Gene Expression in Drosophila immigrans

Regulation of Yolk Protein 2 Gene Expression in Drosophila immigrans

Evolution of the noncoding regions in Drosophila mitochondrial DNA: two intergenic regions.

The sequences of the mitochondrial DNA (mtDNA) segment containing the two intergenic regions were determined for six species belonging to the Drosophila immigrans species group and compared to the corresponding segments of Drosophila species which had been studied previously. We found remarkable differences in the evolutionary rates of the two intergenic regions. The Intergenic I region, which lies between the tRNA(gln) and the tRNA(ile) genes, was found to be highly conserved in terms of both size (30 ntp) and nucleotide sequence among the species studied. In contrast, the sequences of the Intergenic II region, which lies between the tRNA(f-met) and the tRNA(ile) genes, showed considerable variation. The size of the Intergenic II region ranged from 0 to 88 ntp, and accurate alignment was possible only among sequences from geographical strains or very closely related species in the nasuta species subgroup. The observed differences in conservation of the two mtDNA intergenic regions are discussed in light of functional constraints on mtDNA sequences.

Search strategies of fruit flies in steady and shifting winds in the absence of food odours

Abstract. Flight behaviour by females of two species of fruit flies, Drosophila funebris and Drosophila immigrans, was videorecorded in a wind tunnel in still air and in wind with a constant or shifting direction. Flies which were deprived of food overnight took flight in the absence of food odours. Both species responded to the presented winds in agreement with two models that predict the shortest distance to an odour plume. According to these models, the shortest distance to an odour plume is travelled when insects fly at right angles to the wind with a steady direction. In winds shifting over more than 60d̀, the shortest distance to an odour plume is achieved when insects fly parallel to the time‐averaged wind direction. We propose a behavioural mechanism which accomplishes the observed flight directions taken by the two species of fruit flies in response to the tested wind regimes.

Diallel analysis of temperature preference in Drosophila immigrans

Diallel analysis of temperature preference in Drosophila immigrans

Ethanol and acetic-acid tolerance in Indian geographical populations of Drosophila immigrans

Summary - Indian geographical populations of Drosophila immigrans revealed a lack of allozymic variation at the alcohol dehydrogenase locus. Latitudinal clines of ethanol tolerance (1.5-4.2%) and acetic-acid tolerance (2.9-4.9%) were observed in adult individuals of 4 geographical populations of Drosophila immigrans. Thus, both ethanol and acetic-acid tolerance decreased towards the equator. The parallel patterns of utilisation of ethanol and acetic acid seem to be correlated with the concentrations of these 2 metabolites in natural food resources. Thus, intra-specific differences for ethanol and acetic-acid tolerance could be adaptively maintained by spatially varying fermenting habitats along the north-south axis of the Indian sub-continent. ethanol tolerance / acetic-acid tolerance / clinal variation / geographical population / Drosophila immigrans

Diallel analysis of temperature preference in Drosophila immigrans.

The genetic structure of temperature preference of D. immigrans was analyzed by a 4 x 4 diallel cross. Preference for low temperature was dominant to that for high temperature. Partition of the variance showed that most of the variance was additive; the variance caused by dominance was small but significant, and non-additive, non-dominance variance was not significant. Heritability of the temperature preference was 0.81. There may be a few genes involved in variation for temperature preference.