Drosophila Montium Subgroup Research Articles

The pdm3 Locus Is a Hotspot for Recurrent Evolution of Female-Limited Color Dimorphism in Drosophila

Sex-limited polymorphisms are an intriguing form of sexual dimorphism that offer unique opportunities to reconstruct the evolutionary changes that decouple male and female traits encoded by a shared genome. We investigated the genetic basis of a Mendelian female-limited color dimorphism (FLCD) that segregates in natural populations of more than 20 species of the Drosophila montium subgroup. In these species, females have alternative abdominal color morphs, light and dark, whereas males have only one color morph in each species. A comprehensive molecular phylogeny of the montium subgroup supports multiple origins of FLCD. Despite this, we mapped FLCD to the same locus in four distantly related species-the transcription factor POU domain motif3 (pdm3), which acts as a repressor of abdominal pigmentation in D.melanogaster. In D.serrata, FLCD maps to a structural variant in the first intron of pdm3; however, this variant is not found in the three other species-D.kikkawai, D.leontia, and D.burlai-and sequence analysis strongly suggests the pdm3 alleles responsible for FLCD originated independently at least three times. We propose that cis-regulatory changes in pdm3 form sexually dimorphic and monomorphic alleles that segregate within species and are preserved, at least in one species, by structural variation. Surprisingly, pdm3 has not been implicated in the evolution of sex-specific pigmentation outside the montium subgroup, suggesting that the genetic paths to sexual dimorphism may be constrained within a clade but variable across clades.

Variations in the esterase expression pattern with respect to different light regimes in Drosophila agumbensis and Drosophila nagarholensis

Circadian clock enables organism’s to adapt under fluctuating environmental conditions by coupling of behavioral, physiological and molecular processes in a wide variety of organisms including bacteria, fungi, plants, birds and mammals. The endogenous circadian system functions to organize behavior and physiology to adapt to and anticipate environment changes in light and temperature. The present study is an attempt to understand enzyme profiles (alpha- and beta-esterases) of Drosophila agumbensis and Drosophila nagarholensis under light/dark (LD), constant dark (DD) constant light (LL), conditions over twenty generations. A polyacrylamide gel electrophoresis (7.5% – Native gel) was used to study the esterase expression patterns in two species of the montium subgroup of Drosophila. Alpha- and beta-esterase expression was significantly decreased in LL when compared to LD and DD at both the generations and species. In all the light regimes, females were found to have significantly higher level of α- and β-esterase expression than males. Flies were maintained under different light regimes showed difference in their expression patterns with respect to alpha- and beta-esterases. The present study showed that constant light conditions affect the expression of esterases in D. agumbensis and D. nagarholensis.

Effect of different light regimes on fitness of two species of Drosophila montium subgroup

Most organisms possess “biological chronometers” in the form of circadian clocks. Organism possessing circadian clock gains fitness advantage in two ways, by synchronizing its behavior through physiological process and secondly by coordinating its internal metabolic process. Environmental manipulations of circadian clocks have been shown to affect many life-history-related traits. Life-history traits are important components of fitness. To enhance individual fitness, organism has to synchronize the physiology with the surrounding environment. The present investigations were made to understand whether rhythm changes affect fitness of two co-existing species of montium a subgroup of Drosophila. The stocks were maintained at 20 ± 1 °C with 75% RH. Fitness such as fecundity, male lifetime fertility, female lifetime fertility, and longevity was assessed in LD (light/dark), LL (continuous light), and DD (continuous dark) for 15 and 30th generations. Fecundity was assessed in 25 pairs of flies for 20 days, and fertility and longevity was assessed in 10 pairs of flies until lifetime. The result revealed differential effect of light regimes on the two different species of Drosophila. Although the two species are related, effect of the three light regimes, LD, LL, and DD on them was different. It is evident that these two species although genetically related exhibit different responses to different light regimes.

An Evidence of Enhanced Fitness by Male Remounting during the Courtship in three Species of Montium Subgroup of Drosophila

Male mating a second female after first mate (male remating) is a common feature in Drosophila, particularly in mass culture. On the other hand, female remating is not as frequent as that of male remating because the sperms introduced along with the semen into the spermatheca are stored there. However, the phenomena of female remating have been reported in few species. During sexual activity, the males and females are involved an elaborate courtship at the end of which the male mounts on to the female followed by mating. During each mating, the mounted male through its ejaculate, transmits the sperms into the females' genital tract where it is stored. The sperms are stored in the spermatheca. Usually, with one mount maximum sperms are transferred to female hence second mounting does not occur. In most Drosophila, when a male mounts a female after an elaborate courtship, the pairs remain in cupola for a fixed period then dismounts. No more courtship or mounting is performed by the male towards the same female. In D.jambulina, D.nagarholensis and D.gangotrii remounting occurs two or three times immediately after the first mount. The reason for remounting has been analyzed in the present study through measuring the width of the female reproductive tract and sperm count after each mount. The female reproductive tract was dissected out and width of uterus was measured. The result showed significant difference in the width after each mount. The sperm count of these species after each mount also showed significant variation. Remounting perhaps enhances the fitness of the mating pairs.

Copulatory song in three species of the Drosophila montium subgroup extends copulation and shows unusual genetic control

Most Drosophila species produce species-specific male courtship song as part of their precopulatory courtship repertoire. Females usually mate most quickly when stimulated with appropriate song. Unusually, males of Drosophila lini and its sibling species sing sine song only during copulation. Sine song frequency is high in D. lini and Drosophila ogumai and lower in Drosophila ohnishii. Drosophila ogumai and D. lini are allopatric, although the range of D. ohnishii may meet or overlap with that of D. ogumai or D. lini. We conducted playback experiments with each species to examine the role of sine song frequency. Copulation duration increased for females of D. lini or D. ogumai when stimulated with high-frequency (240–250 Hz) artificial song and for females of D. ohnishii when stimulated with low-frequency (170–180 Hz) artificial song. This suggests that sine song frequency extends copulation duration in the three species and that species-typical song is more effective. We also examined song frequency in crosses between D. lini and D. ohnishii to assess its genetic control. Analysis of F1 and backcross generations between D. lini and D. ohnishii showed that sine song frequency is mainly due to additive autosomal variation, although a transgressive effect of the X chromosome and maternal or Y-linked effects were also found.

Horizontal transmission versus vertical inheritance of P elements in Drosophila and Scaptomyza: has the M-type subfamily spread from East Asia?

Polymerase chain reaction (PCR) screening for P elements was carried out in 77 species with a primer set highly specific for the M-type subfamily. In the course of this search M-type elements were detected in 29 species: In the melanogaster (subgroups montium and rhopaloa) and obscura species groups of Drosophila (25 out of 71 species examined), and in the genus Scaptomyza (four out of six species). M-type elements are present in all species of the montium subgroup investigated so far (21), but occur only sporadically in other groups. Within the montium subgroup 20 species possess only incomplete copies, only one species (D. lacteicornis) harbours apparently full-sized elements. In contrast, outside the montium subgroup almost all species with M-type elements carry full-sized copies suggesting transpositional activity, at least in the recent past. The interior section of the full-sized M-type element of D. lacteicornis was partially sequenced (936 bp). In addition, the complete sequences of four internally deleted M-type elements of D. lacteicornis, D. rufa, D. quadraria, and D. triauraria were determined. Sequence comparisons (including sequence data from previous investigations) revealed striking discrepancies between P element phylogeny and the cladogenesis of their host species. Among several possible pathways for interspecific transfers of M-type elements, we favour the hypothesis assuming the invasion of Scaptomyza as well as the obscura group species of Drosophila via independent transmission routes originating from Asian species of the montium subgroup of Drosophila. The logical geographic scenario for these events would be East-Asia.

Localization and Characterization of Heterochromatin among Four Species of the Montium Subgroup of Drosophila

The karyotype of 4 species namely D. agumbensis, D. anomelani, D. truncata and D. cauverii have been analysed. The heterochromatin content has been characterized by using C- and Q-profiles. The Y- and 4th chromosome have shown a great degree of divergence in their form and size. The heterochromatin has played a very important role in bringing about this high degree of differentiation within the limit of 2n=8 among the members of the montium subgroup of Drosophila.

Drosophila bunnanda-a new species from northern Australia with notes on other Australian members of the montium subgroup (Diptera: Drosophilidae)

An unknown Drosophila montium subgroup species was collected on Cape York Peninsula in 1992, a live culture of the same species was established from flies collected in the vicinity of Lake Placid near Cairns in 2001. From these specimens we now have sufficient information to describe a new species—Drosophila bunnanda. It differs morphologically from the four other montium subgroup species already known from northern Queensland—D. serrata, D. birchii, D. kikkawai, and D. sp. cf. jambulina, and from one very similar species—D. dominicana—known from Papua New Guinea. Molecular data support the taxonomic findings. Additional information and a key for all Australian montium subgroup species is provided to allow clear differentiation between them and D. bunnanda.

Evolutionary history and mode of the amylase multigene family in Drosophila.

Previous studies indicate that the tandemly repeated members of the amylase (Amy) gene family evolved in a concerted manner in the melanogaster subgroup and in some other species. In this paper, we analyzed all of the 49 active and complete Amy gene sequences in Drosophila, mostly from subgenus Sophophora. Phylogenetic analysis indicated that the two types of diverged Amy genes in the Drosophila montium subgroup and Drosophila ananassae, which are located in distant chromosomal regions from each other, originated independently in different evolutionary lineages of the melanogaster group after the split of the obscura and melanogaster groups. One of the two clusters was lost after duplication in the melanogaster subgroup. Given the time, 24.9 mya, of divergence between the obscura and the melanogaster groups (Russo et al. 1995), the two duplication events were estimated to occur at about 13.96 +/- 1.93 and 12.38 +/- 1.76 mya in the montium subgroup and D. ananassae, respectively. An accelerated rate of amino acid changes was not observed in either lineage after these gene duplications. However, the G+C contents at the third codon positions (GC3) decreased significantly along one of the two Amy clusters both in the montium subgroup and in D. ananassae right after gene duplication. Furthermore, one of the two types of the Amy genes with a lower GC3 content has lost a specific regulatory element within the montium subgroup species and D. ananassae. While the tandemly repeated members evolved in a concerted manner, the two types of diverged Amy genes in Drosophila experienced frequent gene duplication, gene loss, and divergent evolution following the model of a birth-and-death process.

Isolation, characterization, and localization of beta-tubulin genomic clones of three Drosophila montium subgroup species.

Genomic libraries were constructed from three Drosophila species, namely Drosophila auraria, Drosophila serrata, and Drosophila kikkawai, belonging to the Drosophila montium subgroup of the Drosophila melanogaster species group. Clones containing beta-tubulin specific sequences were isolated, characterized by restriction endonuclease digestions and Southern hybridizations, and mapped by in situ hybridization on the polytene chromosomes of the species studied. The distribution of the beta-tubulin loci was found to be similar in D. montium species and D. melanogaster.

The organization of the alpha-tubulin gene family in the Drosophila montium subgroup of the melanogaster species group.

The alpha 1-, alpha 2-, alpha 3-, and alpha 4-tubulin genes have been mapped by in situ hybridization to the polytene chromosomes of five species representative of the Drosophila montium subgroup geographical distribution. A lambda phage clone containing alpha 1-tubulin specific sequences was isolated from a genomic DNA library of Drosophila auraria and its restriction endonuclease pattern is presented. Both well-characterized heterologous and homologous probes were used to assess orthogonality of gene members between species groups. The in situ hybridization pattern observed in all species studied is consistent with that of Drosophila melanogaster, since alpha 1-, alpha 2-, and alpha 3-tubulin genes are located on the same polytene arm, and the alpha 4-tubulin gene is found on a different arm. Cross-hybridization was observed among alpha 1-, alpha 2-, and alpha 3-tubulin specific sequences in all species studied, using either heterologous or homologous probes. However, unlike D. melanogaster, in all montium species studied, both alpha 1- and alpha 3-tubulin specific probes hybridize to the same polytene band, indicating a clustered organization of the above genes. The chromosomal organization of this gene family would suggest that taxa within the montium subgroup are closer to their common ancestors than are the taxa in the melanogaster species group. A mode of evolution for this gene family in Drosophila is proposed.

The glutamate dehydrogenase, E74 and putative actin gene loci in the Drosophila montium subgroup. Chromosomal homologies among the montium species and D. melanogaster.

DNA-specific sequences from an enzyme-coding gene (glutamate dehydrogenase, gdh), a regulatory protein-coding gene (E74) and genes of the actin family were mapped by in situ hybridization on the polytene chromosomes of six species representative of the geographical distribution of the Drosophila montium subgroup of the melanogaster species group. In all species studied, one hybridization signal was detected for the gdh and E74 genes, and seven signals for the actin genes. The distribution of the actin-related loci in five montium species is similar to that of the other Drosophila species studied so far, although they present an extra signal. This distribution differs in the sixth montium species studied, D. kikkawai. Taking into account the present results, as well as previous data obtained mainly by in situ hybridizations, homologies among the polytene chromosomes of the montium subgroup species, as well as between these species and D. melanogaster, were also established.

Variations in the heat-induced protein pattern of several Drosophila montium subgroup species (Diptera:Drosophilidae).

After temperature elevation, the newly synthesized polypeptides from several Drosophila montium subgroup species, of the melanogaster species group, were analyzed in denaturing acrylamide gels. The pattern obtained is characteristic of the heat shock response already documented for many other Drosophila species, although the relative electrophoretic mobility of the "small" heat shock proteins exhibits a species-specific pattern. Based on the above pattern, the montium species are placed in three distinct groups. The present data is consistent with that previously used to propose a northeast to southwest evolutionary mode of expansion for the montium subgroup species.

Characterization of Heterochromatin in Three Species of the Montium Subgroup of Drosophila.

The heterochromatin of 3 species of the montium subgroup of Drosophila, namely D. nagarholensis, D. jambulina, and D. kikkawai was analyzed. Within the basic karyotypic configuration of 2n = 8, interspecies differences in the pattern and the intensity of C- and Q-band heterochromatin particularly of the Y and dot chromosomes were recorded. [on SciFinder(R)]

The Drosophila montium subgroup species. Phylogenetic relationships based on mitochondrial DNA analysis.

Mitochondrial DNA (mtDNA) restriction site maps for three Drosophila montium subgroup species of the melanogaster species group, inhabiting Indian and Afrotropical montium subgroup territories, were established. Taking into account previous mtDNA data concerning six oriental montium species, a phylogeny was established using distance-matrix and parsimony methods. Both genetic diversity and mtDNA size variations were found to be very narrow, suggesting close phylogenetic relationships among all montium species studied. The phylogenetic trees that were constructed revealed three main lineages for the montium subgroup species studied: one consisting of the Afrotropical species Drosophila seguyi, which is placed distantly from the other species, one comprising the north-oriental (Palearctic) species, and one comprising the southwestern (south-oriental, Australasian, Indian, and Afrotropical) species. The combination of the mtDNA data presented here with data from other species belonging to the melanogaster and obscura subgroups revealed two major clusters: melanogaster and obscura. The melanogaster cluster is further divided into two compact lineages, comprising the montium subgroup species and the melanogaster complex species; the species of the other complex of the melanogaster subgroup, yakuba, disperse among the obscura species. The above grouping is in agreement with the mtDNA size variations of the species. Overall, among all subgroups studied, the species of the montium subgroup seem to be the most closely related.

The heat shock genes in the Drosophila montium subgroup: chromosomal localization and evolutionary implications.

The hsp70, hsp83, hsromega, and the small heat shock protein genes were mapped on the polytene chromosomes of six species, representative of the geographical distribution of the Drosophila montium subgroup of the melanogaster species group. In addition, based on hybridization conditions, the putative locus of the hsp68 gene is given. In contrast to the situation in the melanogaster subgroup species, the hsp70 locus is single in the montium species. The hsp83, hsromega and the small hsp loci are also single in the montium genomes studied here, a common feature of all Drosophila species. Among the hsp genes studied, the small hsp genes and the hsromega-homologous sequences exhibit a higher degree of divergence between the melanogaster and the montium subgroups. Our results support the idea that the montium subgroup species has a genome organization closer to that of the common ancestor compared with the melanogaster subgroup species.

The ?-tubulin gene family evolution in the Drosophila montium subgroup of the melanogaster species group

The beta 1-, beta 2-, and beta 3-tubulin genes have been mapped by in situ hybridization on the polytene chromosomes of 11 selected species (15 strains) belonging to the Drosophila montium subgroup. Although the hybridization pattern among the strains of the same species does not differ, this pattern is significantly different among the species. The beta-tubulin genes in the montium subgroup seem to be organized in a cluster, or in a semicluster or are completely dispersed. The clustered arrangements is found in the North-Oriental sibling species D. auraria, D. triauraria, and D. quadraria. The semiclustered arrangement, wherein the beta 1 and beta 2 genes are located at the same locus while beta 3 is at a different one, appears in the South-Oriental species D. bicornuta, D. serrata, and D. birchii, as well as in the Afrotropical species D. diplacantha and D. seguyi. The complete separation of the genes is observed in the Indian species D. kikkawai and D. jambulina and in the Afrotropical species D. vulcana. Based on the above results, a possible mode of evolution of the beta-tubulin genes in the montium subgroup is attempted. In addition, phylogenetic relationships among the montium species are discussed.

The Chromosomes of Three Species of the Montium Subgroup of Drosophila

Chromosomes of Drosophila truncata, D. nagarholensis, and D. agumbensis of the montium subgroup were analyzed to record the divergence attained at the level of metaphase complement and the extent of inversion polymorphism. Results are presented in this article.

Biochemical phylogeny of seven Indian species of the montium subgroup of Drosophila

Seven species of the montium subgroup of Drosophila found in South India were analysed with polyacrylamide disc electrophoresis. Eleven loci coding for enzymes were surveyed. The genetic distances between species have been measured. The dendrogram revealed three clusters. The first cluster includes D. nagarholensis, D. agumbensis, D. jambulina and D. kikkawai; the second group consists of D. truncata and D. anomelani; while D. mysorensis was the only species of the third group.

Metaphase karyotype differentiation in eight species of the montium subgroup of Drosophila.

The metaphase karyotypes of eight species of the montium species subgroup of Drosophila are described, of which the information pertaining to six species is new to the literature. Each of these species studied was distinctly different from the others with respect to the metaphase chromosomes, this remarkable degree of differentiation being mainly due to the extensive variability of the 4th and of the Y chromosomes.