The flower flies and the unknown diversity of Drosophilidae (Diptera): a biodiversity inventory in the Brazilian fauna

Diptera is a megadiverse order, reaching its peak of diversity in Neotropics, although our knowledge of dipteran fauna from this region is grossly lacking. This applies even to the most studied families, such as Drosophilidae. Despite its prom-inence, most aspects of the biology of these insects are still poorly understood, especially those linked to natural communities. Field studies on drosophilids are highly biased towards fruit-breeding species. Flower-breeding drosophilids, however, are worldwide distributed, especially in tropical regions, although being mostly neglected. The present paper shows the results of a biodiversity inventory of flower-breeding drosophilids carried out in several localities in Brazil, based on samples of 125 plant species, from 47 families. Drosophilids were found in flowers of 56 plant species, from 18 families. The fauna discovered turned out to be mostly unknown, comprising 28 species, with 12 of them (> 40%) still undescribed. Not taking into account oppor-tunistic species, two-thirds of the flower-exclusive diversity was undescribed. The Drosophila bromeliae species group was the most representative taxon, with eight species (six undescribed), including four polyphagous and four Solanum-specialized species. This specialization on Solanum is reported for the first time for Drosophilidae. Other taxa of restricted flower-breeding drosophilids were the Drosophila lutzii species group and two species of the genus Zygothrica Wiedemann. Some specimens of the genera Cladochaeta Coquillett, Rhinoleucophenga Hendel and Scaptomyza Hardy were found, but their relations to flowers are unclear. Additionally, ten species of broad niche were found using flowers opportunistically. Localities and host plants were recorded for all species collected

Interpopulation variation of transposable elements of the hAT superfamily in Drosophila willistoni (Diptera: Drosophilidae): in-situ approach

Transposable elements are abundant and dynamic part of the genome, influencing organisms in different ways through their presence or mobilization, or by acting directly on pre- and post-transcriptional regulatory regions. We compared and evaluated the presence, structure, and copy number of three hAT superfamily transposons (hobo, BuT2, and mar) in five strains of Drosophila willistoni species. These D. willistoni strains are of different geographical origins, sampled across the north-south occurrence of this species. We used sequenced clones of the hAT elements in fluorescence in-situ hybridizations in the polytene chromosomes of three strains of D. willistoni. We also analyzed the structural characteristics and number of copies of these hAT elements in the 10 currently available sequenced genomes of the willistoni group. We found that hobo, BuT2, and mar were widely distributed in D. willistoni polytene chromosomes and sequenced genomes of the willistoni group, except for mar, which is restricted to the subgroup willistoni. Furthermore, the elements hobo, BuT2, and mar have different evolutionary histories. The transposon differences among D. willistoni strains, such as variation in the number, structure, and chromosomal distribution of hAT transposons, could reflect the genomic and chromosomal plasticity of D. willistoni species in adapting to highly variable environments

Study of four Neotropical species of tree crickets Oecanthus Serville, 1831 (Orthoptera, Gryllidae) using cytogenetic and molecular markers

Karyotypes in the worldwide subfamily Oecanthinae show variations in diploid number, chromosome morphology, and sex-chromosome system. This study described the chromosome set and phylogenetic relationships of four Neotropical species, Oecanthus lineolatus, O. valensis, O. pallidus, and O. pictus. We used classical cytogenetics and Bayesian Inference for phylogenetic reconstruction, using the mitochondrial genes COI, 12S rRNA, and 16S rRNA; and analyzed the phylogenetic patterns of changes in chromosome numbers, using ChromEvol. We observed differences in chromosome number among species and two different sex-chromosome systems. Oecanthus pictus showed 2n = 21, X0♂/22, XX♀; O. lineolatus, 2n = 20, XY♂/XX♀; and O. valensis and O. pallidus, 2n = 18, XY♂/XX♀. The karyotype of Oecanthus was asymmetric, one group with large chromosomes and variation in heterochromatin distribution, and another with small acrocentric chromosomes. The phylogenetic tree recovered two main groups: one with the Palearctic species and another with species from different bioregions, but with low posterior probability. The Neotropical species grouped separately, O. valensis and O. pictus with Nearctic and Ethiopian species, and O. pallidus and O. lineolatus in another, well-supported clade. Together, the phylogenic and chromosome data suggest descending dysploidy events during the evolution of the group

Three decades of studies on chromosomal polymorphism of Drosophila willistoni and description of fifty different rearrangements

Drosophila willistoni (Insecta, Diptera) is considered a paradigm for evolutionary studies. Their chromosomes are characterized by multiple paracentric inversions that make it hard to identify and describe chromosomal polymorphisms. In the present report we attempted to systematize the description of all the 50 inversions found in the last three decades, since we have been studying the chromosomes of several individuals of 30 different populations, including the one used in the genome sequencing project (Gd-H4-1). We present the photographic register of 11 arrangements in the left arm of the X chromosome (XL), eight in the right arm (XR), 10 in the left arm of chromosome II (IIL), eight in its right arm (IIR) and 13 in chromosome III. This information also includes their breakpoints on the reference photomap. A clear geographic difference was detected in XL and XR, with different fixed arrangements depending on the origin of the population studied. Through the comparison of all X arrangements it was possible to infer the putative ancestral arrangements, i.e., those related to all the remaining arrangements through the small number of inversions that occurred in the past, which we will call XL-A and XR-A. In the autosomes (IIL/IIR and III), fixed inversions were detected, but most are segregating in different frequencies along the geographical distribution of the D. willistoni populations

Estudo de efeitos geneticos do selenio em drosophila melanogaster

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Distribution and conservation of the transposable element gypsy in Drosophilid species

In an attempt to understand the dynamics of transposable elements (T’S) in the genome of host species, we investigated the distribution, representativeness and conservation of DNA sequences homologous to the Drosophila melanogaster gypsy retrotransposon in 42 drosophilid species. Our results extended the knowledge about the wide distribution of gypsy in the genus Drosophila, including several Neotropical species not previously studied. The gypsy-like sequences showed high divergence compared to the D. melanogaster gypsy element. Furthermore, the conservation of the restriction sites between gypsy sequences from phylogenetically unrelated species pointed to a more complex evolutionary picture, which includes the possibility of the horizontal transfer events already described for this retrotransposon