Abstract 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.

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 poly-morphisms. 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.

O grupo de espécies Drosophila peruensis foi proposto recentemente e inclui quatro táxons: D. atalaia Vilela & Sene, 1982, D. boraceia Vilela & Val, 2004, D. pauliceia Ratcov & Vilela, 2007, D. peruensis Wheeler, 1959. Todas possuem a maioria das cerdas do mesonoto emergindo de manchas escuras, veias transversais esfumaçadas (com exceção de D. atalaia) e hipândrio com formato quadrado e fortemente fusionado aos gonópodes. Neste artigo são descritas duas novas espécies, Drosophila itacorubi sp. nov. e D. paraitacorubi sp. nov., pertencentes a este grupo de espécies. A genitália masculina destas espécies são ilustradas. Uma chave de identificação para as espécies do grupo D. peruensis é fornecida.

The Drosophila peruensis species group was recently proposed and includes four taxa: D. atalaia Vilela & Sene, 1982, D. boraceia Vilela & Val, 2004, D. pauliceia Ratcov & Vilela, 2007, and D. peruensis Wheeler, 1959. All these species have most of setae or setulae of mesonotum arinsing from dark spots, wings with crossveins darker (except in D. atalaia) and hypandrium squared-shaped mostly fused to gonopods. Here, we describe two new species, Drosophila itacorubi sp. nov. and Drosophila paraitacorubi sp. nov., belonging to this species group. The male genitalia of these species are figured. An identification key to the D. peruensis species group is provided.

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.

Using conventional staining with acetic orcein and C-banding techniques it was investigated constitutive heterochromatin chromosomal polymorphisms and the mitotic and the meiotic behavior of male and female chromosomes of Boophilus microplus (Canestrini, 1887). Some differences were detected in the population of southern Brazil as compared to the data of other authors for populations in other latitudes. The differences being mainly concerned with the distribution of constitutive centromeric heterochromatin and variation in the length of heterochromatic blocks in the pericentromeric regions of some chromosome pairs.